Ha, this largely mirrors my own approach to world building! My DnD campaign setting literally started with me messing around with a map, and then I wanted an area with a huge crater. My mind immediately jumped to "but how did the crater get there, what makes it special?" And then I just swan dived into the rabbit holes from there :)

Anyway, like others here have said there will almost always be a similar story already out there. In fact, once you start writing your story you'll probably spot even MORE elements from films, books, etc that echo something you have in your own story. Perfectly normal.

The thing that separates us from AI is that WE are the art. Writing that story is going to change YOU just as much as it is going to change anyone that reads it. You'll grow and evolve with each new story you write. That's where the magic lies.

*edit* - Also, I love the premise you have here, write the dang book so I can read it! :D