So my fears are kind of taking over my enjoyment of writing my book because I feel I'm doing something wrong. In my story I stole ideas from other stories. I took the idea of Bioshock's infinite society and parallel worlds. I took Bloodborne's ideas of dreams, where my main antagonist is someone in a place like the hunter's dream. I took the idea of my character and his goal like Full Metal Alchemist (missing a body part and looking for the philosopher's stone). I have always heard that an author should steal like an artist but not copy but my emotions make me feel like my work may be seen as plagiarized.
There are no new ideas. Everything has been done. Every plot device has been used a thousand times. Whatever you write it will use ideas that other writers have already used many times over.
Plagiarism is representing someone else's work as your own. It is not using ideas that have been used before. If it were that, literature would have come to an end eons ago.
What sets one story apart from another is not the ideas in the story or the shape of the story (it is well said that there are only seven plots in fiction) but the individual and specific telling of the story.
The basic girl meets boy, girl scorns boy, girl discovers boy is good egg after all, girl discovers other girl figured this out already, girl wins boy over because they are destined to be soulmates story is told thousands of times, with production on an industrial scale. There is a large group of readers who will consume 50 or 100 versions of that story a year. But each telling of that story has to be particular in its details and the way it is told.
There are no new story ideas left to tell, but there are an infinite number of ways to tell the old stories again. Focus on creating a unique and compelling telling of whichever old stories you choose to tell again.
The question whether or not you may use ideas, characters, stories, and so on from other works has been addressed multiple times on this site, among others in the questions that Michael Kjörling has linked to in his comments, and you will find more if you use the site search.
The short answer is: It is a normal aspect of writing to be inspired by other works of art, and a certain amount of similarity is not only unavoidable but even expected of works within a certain genre. If you process what you take from other works and create something new and original from it, you (probably – we're not lawyers here) aren't plagiarizing.
The legal aspect of your question has been answered to the best of our ability. What I would like to address here is how you feel about what you do and what that means for you as an artist.
If I understand your question correctly, you are not only worried about legal trouble, but also unsure about your status as an artist. Your concern, if I'm not mistaken, is that it seems to you that you have no ideas of your own, that you aren't in fact creative at all, but only an imitator, a copycat, a wannabe.
I haven't read anything your wrote (and am not familiar with most of the works you have used as inspiration), and have only your brief self-description to go by, so I don't really know who you are and what you do. But I can maybe offer you some general thoughts on the matter.
We all, from Homer to Goethe to everyone here on this site, have begun with emulating the artists whom we admire. All our first works were attempts to recreate (aspects of) other works as exactly as possible.
There is no problem with this at all. It is a normal step in the development of one's own unique artistic vision and voice. If you understand what you do now not as your opus magnum but as learning to write, you are on the right path. (Here are some statistics that show how many books authors have written before their debut novel was published. It is very sobering for those of use who still think their first ever book will become a bestseller... )
Many authors do not aim for originality at all. They consider themselves craftspersons who execute the ideas of others. Ghostwriters are an example for this, but also many screenwriters or (pulp) series authors who are given a storyline, characters, and setting to flesh out.
I have written many comissioned works, and although they contained not a single original idea of mine, writing them was great fun and extremely satisfying. Maybe you are the kind of writer who will excel at this kind of teamwork.
Maybe what you are "doing wrong" is that you have allowed yourself to become lost in everything you love about the works of others, and what you need to do now is take a break from writing (and planning etc.), let what you have done rest, and take some time to come to your own senses.
For a while, stop consuming the works of others (or at least those works that are related to your current project, i.e. avoid the same genre) and just live your life: work, study, spend time with friends, do sports, travel, and so on. And while your "writing mind" is thus unoccupied and idle, observe what thoughts and emotions emerge from that part of yourself. Don't judge it, just write everything in a notebook for a while. And after some time, I am sure, an idea of your own will begin to take shape and you will understand what the story is that you want to tell with all those pieces from other works.
From that understanding, the characters, plot, and setting you thought you had stolen from other works, suddenly take on another meaning. They will no longer be "from another book", but about you, and you will find that they begin to change, as you write them, and become your own.
Originality is not a yes/no, true/false thing. There are degrees of originality.
There are lots of stories about a boy and girl who meet and fall in love. They are not all rip-offs of "Romeo and Juliet". Falling in love is part of the normal human experience.
There are lots of stories about a hero who sets off on a quest and must overcome various obstacles to reach his goal. They are not all rip-offs of "The Odyssey". Having a goal and having to overcome obstacles to achieve that goal is part of the normal human experience.
There are lots of stories out there about a brilliant detective solving crimes, couples falling in love, soldiers going to war, a family going through amusing little problems, etc.
It is very rare for an author to come up with a totally original idea. Most writing is coming up with interesting variations of an existing idea.
If you're worried that your story is just like some other author's story because your story has parallel worlds and this other story has parallel worlds ... that's very general. I wouldn't be worried about copying there at all. At the other extreme, if your story is a word-for-word copy of Harry Potter except that you changed the names of all the people and places, I'd say your originality -- coming up with new names -- is so low that you really should try something else. (Never mind that you would surely lose a copyright suit.)
Without reading your story, I can't say how original or unoriginal it is. (And I've never heard of most of the inspirations you mention, so I couldn't judge the similarity.) But the question to ask yourself is, Did I just steal somebody else's idea, or did I steal his idea and then add my own twist to it?
If -- to take something popular enough that most readers will have at least heard of it -- you too Star Wars and shuffled a few details around but basically kept the same story, boring, unoriginal. But if you changed it so that your Darth Vader character was the good guy and your Luke Skywalker was the villain, that the rebels are a bunch of evil terrorists trying to destroy civilization and the empire is trying to preserve it, you would have an original story. Whether it is good or not would depend on how well you did it.
Lots of science fiction stories take real historical events and re-tell them set in the future. To take a classic example, Isaac Asimov's Foundation series is a retelling of the fall of the Roman Empire as the fall of a Galactic Empire. I don't think Asimov was ever shy about admitting that that's exactly what he was doing. He didn't see any reason to be embarrassed about copying historical events. There was a science fiction story I read many years ago (don't remember the title or the author, sorry), about an advanced alien civilization coming to Earth, and the author not only copied many elements of the story from the British colonization of Australia, but throughout the book he pointed out that he was doing this. Characters would say, "This is like when the British did such-and-such with the aborigines".
So ... try to be original. Evaluate how original you think you are being. Don't panic if you are not 100% original.
I am not a lawyer, but do business with copyright law, and this is my understanding.
First, it IS possible to copyright characters in other works. Here is an excerpt from Protection of Fictional Characters:
Although the decisions in cases involving the protection of fictional characters have not been consistent, the prevailing view has been that fictional characters are copyright protected. However, the general trend with respect to copyright protection must be categorized as one of restrictive protection rather than an all-encompassing scope of protection. Generally in those cases where the fictional character was found to be protected, the character that was copied was "distinctively delineated" (or fully developed) in the original work and that the character's delineation was misappropriated in the copier's work.
Also, even if you do not violate copyright, you may violate trademark law; a trademark can be a "phrase" of just a few words, and no filing is required in the USA: A trademark is established when it is used in trade, so if they sold a book a trade occurred. So, if you stole not just the "bioshock infinite society" idea but the name as well, you may be deemed to have violated a trademark of the original author, since this combination of words is likely unique and used by the original author to make money. This is called, under trademark law,
Misappropriation: defined by one court as the "taking and use of another's property for the sole purpose of capitalizing unfairly on the good will and reputation of the property owner." (See here). The discussion of the link is "literary titles", but I believe it has been contested for other unique elements of a work, including character names ("Marty McFly", "James Bond", "Harry Potter").
If what you are interested in is sales, then regardless of whether your use is legal or not, both editors and readers may reject your work for being too obviously a ripoff of another author's ideas, names, and characters.
Many characters look for the philosopher's stone, but how many are "missing a body part?" If you cannot name another character "missing a body part and looking for the philosopher stone" then you may be in copyright violation, especially if your protagonist is similar in other ways to your "inspiration".
So even if you aren't sued, well-read editors or readers or critics may reject your work as unoriginal, a rip-off, or for a publisher, not worth risking a lawsuit.
You can steal ideas, and portrayals that exist in multiple works: Dragons, elves, trolls, witches, wizards and magicians abound. Time travel, parallel worlds, Artificial Intelligence and robots too. Stealing too specifically might get you in legal trouble, or just rejected.
I think the best way to make sure you are not lifting something from another work is to "steal" ideas, but not straight-up concepts.
Have parallel worlds--many authors have before--but make it different, even just a little. Some of my favorite books use them. E.g. Howl's Moving Castle and the Shades of Magic books, but both books are VERY different. Though both involve magicians/wizards as well.
Have a city floating in the air (or is Infinite underwater?), but don't make it steampunk.
Have a world in between that lets you travel quickly to the world outside like in Bloodborne, but make it a carnival setting or something instead.
Have your character search for the philosopher's stone. The philosopher stone in is hundreds of books. Or have them search for the fountain of youth. Or search for a flower pot that does exactly what the philosopher's stone does but it's different now. Give it a new name.
None of the things I mentioned above are unique. All of them have been done before, combining them in a way only you can will make your story YOURS. I don't know if you're just worried about being called out or if you're having more of an existential crisis on the nature of being a writer, but I think every writer wonders from time to time if they are a hack. Welcome to the club!
Also, beta readers and critique partners are invaluable and will let you know if they think your book is too similar to something else. Though, again, many books are similar. People like reading about the same kind of things over and over. That's why books and movies and tv shows have a "if you liked these, you'll love this!" pitch.
Though, maybe don't have your MC be missing an arm and a leg that has been replaced by robot armor while he's looking for that stone. ;)