I suspect you are too focused on your idea. Most ideas for good novel length (or series length) stories are actually pretty simple, and can be summarized in a page. That includes best sellers like The Lord of the Rings, Harry Potter, or The Da Vinci Code.
And those one page summaries, or a synopsis, when we read them, are not that exciting, they are bland. It takes a professional editor, director, script analyst or fellow author steeped in the craft of writing to see such a synopsis as describing a vehicle for entertainment, not as being itself entertaining.
It is an extreme form of "telling, not showing" and I suspect that is what you are writing.
Either that, or like a lot of beginning authors, you are writing story climaxes, and they fall flat and feel boring. There are several such climaxes in the story: The MC being thrown out of their status quo world, halfway through Act I, then seeing the full shape of their problem, end of Act I, their striving to solve it, their setbacks, their final do-or-die conflict and prevailing or failing, near the end of Act III, then the end-of-story denouement or aftermath that completes the emotional journey for the MC.
Unfortunately, the climaxes are boring too, because readers don't care about these characters as much as you do. They are introduced cold, we are neutral on the MC, on the villain (if you have one), on any love story or hate story, on all of it. Readers begin their relationship with your story willing to make a friend of the MC, flawed or not, and wanting to root for someone. But that takes time and showing the reader scenes in which your MC does something they can feel something about.
What turns either a synopsis or a list of climaxes into entertainment is adding a lot of detail and scenes filled with conflict on every page that keeps them reading to find out what happens next. First to introduce your character to them in a non-climax setting (their status quo world), then introducing a complication, that becomes a big problem, that drives them to metaphorically leave the status quo world (physically or mentally or morally) to solve it: The moment Harry Potter turns eleven he discovers he is a wizard via the giant Hagrid pounding on his door, and gets whisked off to a new land and new life in Hogwarts, the school for wizardry.
If you did not know that story it might sound pedestrian, even stupid: Since when is "Harry Potter" the name of a wizard? We don't care anything about this kid, or Hagrid, it sounds like a spoof: A very unwizardly commoner name "Harry Potter", and a laughable silly school name, "Hog Warts".
But it is the author's job to make us care about Harry and Hagrid. She purposely chose a common name for her MC and his friends precisely to appeal to her audience, born without wizardly names, to help them be those characters.
That takes imagination and scenes, scenes, scenes, so we care about the MC and what is happening to them. It takes setups: Nobody cares if Alice breaks up with Bobby. We care only if we see Alice as a friend, or a Bobby as a friend, and although we are willing on either front, if we first see them as strangers on the street yelling and cursing at each other, we care very little. Let us live with Alice a few days and see her "status quo", her happy relationship with Bobby before any instigating incident that will lead to their breakup, and then we like Alice, and we don't like that Bobby has hurt her so badly.
Stories take time to unfold, that time is represented in scenes. If all you write is climaxes, the story is boring, even if your ideas are good enough to be bestsellers or great movies. Take your one-day jottings and treat them as the seed of a story; and write 20 pages introducing your MC, in her status quo world whatever it is, encountering the difficulties of life and work and relationships (in family, romance, work and public) and demands on her time and money and getting her crap done every day. It makes no difference if she is a master assassin or a normal ten year old, everyday life is a routine that can go awry every day.
A great plot can be the skeleton of a great story, but all plots are crap without characters we care about. We feel little sympathy for a skeleton, it needs flesh to become Alice, alone and afraid in her life.
The Sixth Sense is a great plot with a great twist, but if I give you a five sentence, twist-revealing, one-paragraph synopsis without characters, it falls flat, or at best gets a chuckle: "Oh, cool, ha ha."
It has no impact because we have skipped the experiences of seeing a kid terrified, the problems of the psychiatrist with his wife, his guilt over his inability to help a previous similar patient, his slow conversion to believing the supernatural ability, and then the shock of learning the full truth about himself. If we don't care about these people, if they are just skeletons, we do not feel happy with them, fear for them, root for them, grieve with them or dread what will happen to them. Make us like them, and dislike their opponents or their situation or whatever is not right in their world.
Then you will have a story.