That is overly reductive and conflates copying (like a cover band) and creating something new (being influenced). Heck, even when some bands play new versions of existing songs they are adding their own personal touch and have the possibility of making it mean something new. Like how Hurt by NIN and Johnny Cash are the same song, but how they are performed ends up being about completely different experiences.

Even when bands like Led Zeppelin outright covered existing songs they added something to it that AI can't, and won't be able to do. AI can't have sexually charged energy that a human can have. They can pretend to, like how cover bands can pretend to be like the band they are covering, but AI won't be able to replicate the personal touch that memorable art has.

Even popular stuff with widespread appeal frequently drops off over time because it isn't the type of art that holds up over time. Hell, the Beatles mostly hold up more for when they were popular and how they have managed their legacy than any kind of technical prowess in musicianship. Without their performances, their personas, and the backstory to most of their music it is just well done music that has been superseded musically since that time. None of that will apply to AI, and without the backstory it will just end up being high quality music that won't stand the test of time because we don't have any context for it.

Hell, there were a ton of other composers during Beethoven's time that were putting out great music too, but you know who he is because of details other than his musical prowess.