It was pretty obvious to me, but the train of thought was something like this:

* this is a good attempt at a work of art, but written in a generic style that detracts from it * nobody making genuinely good attempts at art like this would also write so generically * and if they were making it generic on purpose, they wouldn't be able to do it so flawlessly * oh, it must be AI

I guess I can discern the presence of a human artist, but only in the idea, which just means it was a good prompt.