So generally there is a tier of characters and how many you should have.
Hero/Perspective Character- There should be only one of these, though it's not a hard rule and not necessarily required either. This should be the character through who's "eyes" the audience witnesses the story. If the story is first person, it's the narrator's character, if the story is third person, it should be the only person who the audience is aware of internal thoughts (unless you're roving camera perspective... then it should be your hero or a character who is acting as narrator after the fact). If you intend to flip perspectives in the story, they should be along hard shifts in the story's scene (If character A and B are both perspective characters, A should not be a perspective character in the same scene where B is a perspective character and vice versa, and you need a hard break like a new chapter to switch from one to the other. I generally tend to obey a soft rule that if A is the POV in a chapter and B is within his sense limits, I should not change to B unless B moves out of A's perspective and B's actions can't bee observed by A. For a good visual look at this, the first Marvel's Avengers scene has a "Oner" in the climax (it concludes with Hulk punching Thor and sending him off screen after killing an alien ship). In this scene, we see each Avenger take actions that show them coming into contact with another member of the team, who is then the focus of the scene with while the former focus character moves off scene and we watch the new character do his/her thing, who will eventually pass off the camera's focus to a new character. The scene, if I recall, starts with Widow dog fighting with aliens, as Iron Man flies past her, and shoots other aliens before landing, and tag teaming with Captain America on the bridge, and then zipping off to pass Halkeye, firing arrows at ground troops, as Hulk leaps past him onto a ship, where he assists Thor who is attempting to fight off troops and down the craft.). Also note, that here Hero does not denote morality. A hero doesn't have to save people or help them or uphold a noble morality, but rather, will "interact with the story". Walter White is the "hero" of Breaking Bad, but no one will say that White is a "good guy" by any stretch of the imagination. He's at best the lesser of two evils... and even then that's open for much debate.
Main Character- Typically and simply there should also be one, but you can have as many as you like. If you have more than one, they either serve as close support and relationships to the hero/perspective character of the story. If you wish to tell portions of the story from their perspective, then this is an ensemble piece. Consider the difference between Harry Potter books and films, where most of the story's actions are from Harry's perspective, compared to Star Wars (where Luke, Han, and Leia may be doing different things simultaneously, but not in the same scene), or Star Trek (Especially TNG and DS9, where an episode will feature a story about one of the senior staff and is told from his/her perspective, with other members of the cast featuring only to fill that story's needs (or contracts... in American television shows, if your name is in the credits, you have to appear in a negotiated number of stories per season by contract. This doesn't mean it has to be anymore than a "Hello, I'm just passing through on my way to the payroll office, carry on" from the guy playing the Captain (Usually the hero in Star Trek)). A good rule for main characters is that they will provide important moments to the story and the hero/focus of the story.
Protaganist- All main characters, including the hero, who's primary motivation aligns with the hero to accomplish the story's goals. It's not important that they have the same goals. One could be on a quest to find and kill his daughter's kidnappers, and the other could be a coerced agent of the kidnappers who helps the father in his quest because he seeks redemption for his prior immoral actions. They are aligned in that they both need to fight the kidnappers to achieve their goal, but they are not aligned in that they have to have the same reason for needing to conclude their actions. Characters may move in and out of this role as the story's events change the circumstances of the goal. Consider Han Solo and Luke Skywalker in A New Hope, where Luke is motivated by adventure and the autistic fight against the empire (and when we meet him, he's really motivated by going anywhere other than Tatooine. He mentions going to an Imperial Academy over dinner and is overjoyed to learn that C-3P0 is a member of the Rebel Alliance. He initially doesn't care who he leaves it, so long as he's not stuck to a life of being a farm hand on his uncles moisture farm. His allegiences only shift wholly to the Rebels after the Imperials kill his uncle and aunt.). Han, meanwhile, is in debt to a ganster and while he has no love of the empire, because they get in his way as a smuggler, he's no fan of the rebels because they don't pay his debts. They're endgames are not the same, but Han has a ship and a need for money and Luke has money and a need to get to the rebels. Luke as a heroic archtype is all gung-ho for saving Leia while Han is more than happy to not get involved... until Luke mentions that she's a princess and royals tend to have more money then smugglers with mob debts that are past due. Here, their goal of "save the princess" align, even though their reason for saving her (moral vs. material reward) are in conflict (in a grand scale. Luke's more than willing to use Han's material concerns as motivation).
Antagonists- The opposite of the protagonists, these encompasses characters that are opposed to the goals of your protaganists. Generally they tend to lead the hero into Man vs. Man, Man vs. Nature, or Man vs. Machine conflicts and need not be sentient to be antagonistic (Man vs. Society tends to be a fourth category, though I tend to think of it as a Man vs. Man or Man vs. Machine subcategory depending on how the antagonists implements it's role on the hero). Like protagonists, an antagonist character to the hero need not be an evil or mortally corrupt individual and switch to a protagonist. Rather, an antagonist takes actions that will hinder the protagonists accomplishments of the goals. Man vs. Nature stories will feature the protaganist's fight against a hostile environment that does not care one iota if the hero lives or dies. Avatar: The Last Airbender has a brilliant line that introduces this idea. In her introductionary scene, Princess Azula is informed by her ships captain that they cannot put into port within her schedule because the tides will not allow it. Azula proceeds to ask the captain what would the tides do if she ordered him to be tossed overboard, to which the guard correctly answers that the tides would violently kill him by tossing him against the ship and rocks. Azula then points out that the captain shouldn't concern himself with what the tides will due if he defies them, as everyone knows that they'll kill him no matter what... he should concern himself with what she will do if he defies her orders because she hasn't committed to tossing him overboard yet. Not only does it compare Azula's antagonistic role to the character she will be replacing from the previous season (who at this point, is reconsidering his goals) while her goals are static, but also highlights that an antagonist need not be anything more than the unemotional forces of nature vs. the defiance of its attempts at limitations. When the antagonist is actively targeting the hero to counter his/her goals, the Antagonist is the most important character you will write in your story as the best ones are often written in a way that they can see themselves as the moral hero of the story (Thanos in Avengers: Infinity War is pure antagonist, but arguably is the "hero" in that we are following his hardships to achieve success. It's a story of a single parent of six adopted and beloved children, who's attempt to save the universe costs him the lives of five of those children and alienates his one surviving daughter to the point that she is ready and willing to assist his enemies. Of course, it's the morality of his goal that makes him the antagonist as the audience is not on his side... but it doesn't mean they see him as outright evil, so much as misguided... we are after-all, made very aware, Thanos is very much capable of loving people and is empathetic to those who stand in his way.).
Antagonist also need not be the villains of a story. I have argued that in Disney's Mulan, the villain, Shan Yu (the leader of the Huns) is a poor Disney villain specifically because he isn't Mulan's antagonist. His goal is to conquer China, while Mulan's goal is to prevent her father's death during his conquest of China. These aren't conflicting goals and there are plenty of ways for Shan Yu and Mulan to both get what they want. Mulan's solution is to join the army in her fathers place, and the major impediment to that isn't Shan Yu (who in their final battle, considers her the most dangerous person and moves to kill her before more valuable military officers) but Chinese societies strict adherence to gender roles (A man vs. Machine conflict, via Man vs. Machine. This isn't the man made constructs' specific and unrelenting targeting of her, but rather the machine's inability to adapt to all possibilities) which prevent Mulan from joining the army (her own father even tells her to keep quiet when she tries to point out that he's too old and injured to go to war, going so far as to give his wife his cane and walk proudly to receive his conscription notice and return to his own house, openly showing to the village that Mulan is wrong in order to save face for his reprieved dishonor from her outburst. This is in sharp contrast to the man who is actively trying to kill her in the climax, who never once refers to Mulan by her gender, and only identifies her as "The soldier from the Mountain" who wiped out his army of 1000s of men despite being hopelessly outnumbered (with a single rocket no less) and handed him his only defeat in the entire war he's waging. Yes, she's a woman, but more importantly, she's the most dangerous person in the room to him, bar none.). Antagonists are generally opposite forces to the the Hero's forward direction and need not even be characters, let alone ones capable of morally justifying their actions.
Secondary characters are generally characters who are written to fill appropriate scenes but their actions tend to take place "off screen" from the heroes actions and will generally fill out the heroes immediate world. They are not necessarily protagonists in that they are not useful to the heroes achievements, but they are not antagonistic in so far as they are working in opposition to the hero. They tend to represent innocents or non-actors who are important in moving plot, but not directly involved. Aunt May, of Spider-Man, is an example of a secondary character (Spider-Man has a great source of secondary characters) as she is someone who is involved with Peter's life through relations unrelated to his heroic actions. May can be a minor protaganist, in that she will often defend Peter because she is his family and guardian, but antagonistic in that often her expectations of Peter and his duties conflict in ways that will complicate his Super heroics (from being kidnapped, or even needing Peter to deliver her prescription meds while Green Goblin is robbing banks in the opposite direction). Similarly, J. Jonah Jamerson is also a secondary character in that he employs Peter, but makes Spider-man's life a living hell, though he is a consummate professional that he will defend his employees from villains who don't like that they printed the truth (though he's prone to first cheering the villains because of his dislike of Spider-man). Typically the round out the primary cast's lives and exist soley through relationships in their daily lives, but not constant presences. While your villain may fit this description as they aren't always encountering the hero directly, the main villain is typically is proactive and thus, moves the plot significantly enough that they don't have to be in every scene with the hero to be important.
Tertiary characters - Typically, unnamed, though if named, they generally are seen as recurring back ground characters and fans may latch onto them because they are quirky (especially in visual mediums) and can be picked out of crowd shots. Other times, they may be a memorable one scene wonder or all purpose merchant.
Static and dynamic characters denote the character's inability or ability to change over the course of the story. One can be a static protagonist or antagonist or a dynamic protagonist or antagonist. Because the perspective character is usually there for the audience to see the world as they perceive it, they will often be dynamic over the course of the story, as they learn to overcome the antagonists forces. Dynamic characters need not directly acknowledge the change out of pride (having someone who you bicker with frequently say something kind to you means you have to sacrifice your previous position to accept the compliment... a proud dynamic character might try to justify how this seeming change wasn't a change, but a nuanced read of his previous character. It's subtle because the justification will now change the character from applying the letter of the law to the spirit of the law). One of the best Dynamic characters ever written is Ebenezer Scrooge, as the whole purpose of the book is to show Scrooge wasn't always the miserable person we first meet, and that he may have made wrong choices in the past, but only he is being miserable in the present about them, and that his misery does impact others even if the doesn't see it. Naturally, Scrooge does get the jist of what the Spirits are trying to show him by the time the Ghost of Christmas Yet to Come arrives (normally it's when the Ghost of Christmas Present throws Scrooges' "If they'd rather die, then they better do it" line from the first act) to the point that this Ghost let's Scrooge figure it out for himself and just points at stuff he wants the man to notice. Scrooge does try and beat around the bush, but he's clearly aware of the answer but too afraid to say it himself. During the sequence where he commits to being a better person, Scrooge is well aware of the fact that everyone he is apologizing too is going to be weirded out by this and the story of the three ghosts is too fantastic to keep them from being skeptical, and plays with it... Consider that when Scrooge for the first time visits Bob Kratchet and his family in a form they can see, he damn near has the entire family convinced he's about to fire Bob on Christmas Day before revealing he's giving Bob a huge raise and offers to treat the whole family to feast in Bob's honor on his own dime. Here, Scrooge is the only character who is dynamic and changes through the events of the story (Marley could be argued, but the story opens with the narrator breaking the forth wall to make sure there was no uncertainty in the readers mind that Marley had been dead for some time prior to the events of the story... so that when Marley does appear, we can see that his present state is because he was just like Scrooge and never repented until he died and was doomed for all enternity to wear his mistakes as a heavy chain upon his soul... he only became remorseful after death, but the reader only sees him onscreen as this. His situation remains the same at the stories conclusion and Marley specificly points out that he wore the same chain in life but wasn't aware of it... and tells Scrooge that he can see the chain scrooge is currently wearing and it's a lot worse than the one Marley wears that is clearly terrifying Scrooge. Since the events of the future can be changed, the Cratchets are never permitted to actually change the happy family of the Present Christmas to the grieving framily of the future, and while the people of the past may not accept Scrooge's apologies, it does not stop Scrooge from making amends, and the novel concludes that he more than made good on his promise to be a better person (this can even be seen a subtle acknowledging Scrooge having a spiritual read of the former letter of his personal code: Scrooge is a money lender... he's more than aware that any debt, be it in money or in one's mortal soul, must be paid back in full... with interest. Scrooge still has this mindset, but now he's keeping his spiritual books in the black in addition to his fiscal books... ignore the double meaning of keeping one's soul black, its a financial metaphor.).