It's weird when someone reads your manuscript and makes an observation like, "It's basically the Cinderella story," when such a thing never crossed your mind. But that is one of the perks of sharing your work with others. Under circumstances like that, clearly something subconscious was taking place.
Years ago I started writing a series of supernatural short stories that involved a young woman, her brother, and her male cousin. While reading a book about Greek mythology, I realized the young woman and her brother were variations on the siblings Diana and Apollo; their cousin was a lot like Narcissus.