My initial response to this was to think of all the artists who don't actually create their own work. Lots of contemporary artists have assistants that do the actual painting, sculpting, installation, etc. Even way back a lot of masters were credited for work that was done by apprentices.

But, then on the other hand I suppose that in the eyes of the law, a monkey can't legally sign a contract agreeing to pass ownership over to the person 'employing' them as an assistant.

It's a strange grey area though – Warhol's whole thing was how the factory made the art. People have been making generative art for decades before AI came along, and as far as I know – and I went to school for Art and studied Art History pretty extensively – people just said, "oh that's a cool way to call ownership and authenticity into question." But generally nobody doubted that like, Damien Hirst is the copyright holder of his works even if an assistant makes it – and even if they have no formal piece of paper that lays it all out.