I think the biggest fundamental difference is that we respect human creativity even when it is learned, because of the value in rights we ascribe to humans. It is expected and natural for humans to fairly use things they have learned as a part of an otherwise unique work. But do we ascribe the same privileges to a machine, particularly when it can be automated? The opportunity cost of the human experience itself is the reason why we even have copy rights.

There is also the other way, humans are laundering AI code, and making it look like they wrote the code, to register copyright to their own name.