Well, all you've told us are that you are changing the characters, plot, and setting. Those are the only parts of a story. It depends how much you change them. Also, everyone steals. Pick any famous piece of media or literature. Let's say West Side Story. Everyone knows that's derived from Romeo and Juliet But Romeo and Juliet is almost identical to many much older stories, and no one noticed, and when they did, they didn't care. They just said, "But he did it way better." Also, Disney's the Lion King is just Hamlet but with lions instead of people and music. The second Lion King is just Romeo and Juliet, but no one cares about that movie.