I've been thinking of the output as fanfiction/fan art. It shares many of the same complications regarding the ownership of ideas, commerical intent of writing, competition, and copyright. Fanfiction is generally a protected form of expression, but requires the work to be "transformative". Unlike with parodies and critisisms, fanfiction can be much harder to distinguish from original work. From that perspective, a large amount of the output of LLMs is so generic, that it's not possible to attribute it to one person. It's like trying to find the original author of "Once upon a time".

https://theinnisherald.com/the-other-once-upon-a-times-a-his...