Everything is arguably based on something else somewhere along the line. But the fact that there are people who want to create new material within the specific fictional universe created proves that, the fictional universe is in itself has a value. If people don't want to take it and run, but instead felt the need to develop it into something different, well then....it's a new IP. And the owners of the original IP deserve nothing. They stole their idea from somewhere else to begin with, didn't they?
Picasso said every wise word that needs to be said on this subject. He had his **** together and probably created more original content than any other man alive or dead.