There’s no way you’d be able to tell.
Uh, have you actually listened to any of it? At all?
There are some non-Western traditional types of music I'd agree can have a level of complexity not usually encountered within the Western classical or jazz genres, but it's fair to say all over forms of Western music are vastly simpler in terms of harmonic language, tonality, form/ structure, instrumentation etc. None of which I believe would make it harder for AIs to generate, as computers can manage complexity rather well. What I expect AIs to not be good at is to conjure a truly original and distinct sound world significantly different to anything that's come before, but that still captivates audiences. Which is arguably what the greatest human composers & musicians have generally achieved, in any genre.
AI would need to be able to do something like create The Bad Plus in 1995. That's an even bigger mountain to climb.
People will still want to create their sound, and that'll lead to new music over time that isn't just imitation.
Have you ever heard of Ella Fitzgerald?
EG: Read something like George Russell's "The Lydian Chromatic Concept of Tonal Organization" (the basis from which modal jazz sprung, which includes one of the most famous jazz albums of all time, Miles Davis's "Kind of Blue"). Now add to the theory the ability to improvise around it as good as a Miles Davis level jazz performer can. It's not technically easy at all.
Even if other music genres are much technically easier, so much of music is the social experience anyways.
Take punk music. Though some parts got more technical later, much of it (particularly the late 1970s / early 1980s stuff) is, in my opinion, very technically easy; not too challenging to play, with very basic music structure (which was half the point, a return to rock's garage roots).
I'm guessing an AI can probably be developed (especially with today's fairly realistic sounding guitar VSTs) to make some "technically correct" old school punk rock, certainly much easier than it can be programmed to make "technically correct" modal jazz. An AI, however, cannot replicate the human parts, eg the social or community aspects of a music scene. Which with a lot of music is a huge portion of the point (certainly for punk it was).