Harry Potter, Spiderman, Superman, The Dark Crystal, Ironman, The Green Hornet, James Bond / 007 types, The Chronicles of Narnia, and others . If you believe that this is true, what do you think mankind is searching for? It isn't just America, for instance there are movies being created in the Asian market that also contain these types of characters, like Final Fantasy.
Good question. Maybe it's because we've forgotten God.
I think they are trying in a back handed way establish the idea of evolution.