I don't think we really even need to dive that deep into the philosophical aspect of this. I think that it's fine to simply treat humans and machines differently, the same way we decided that animals cannot hold copyright for a work.

The reason copyright law exists in the first place is due to the difference of scale between copying books by hand and using a machine to do it, so I think "it's different because a machine is doing it" is a completely rational stance to take.