They are not. A derivative would be a translation, or theater play, nowadays, a game, or movie. Even stuff set in the same universe.

Expanding the meaning of “derivative” so massively would mean that pretty much any piece of code ever written is a derivative of technical documentation and even textbooks.

So far, judges simply throw out these theories, without even debating them in court. Society would have to move a lot further to the right, still, before these ideas become realistic.