Dear Google: Public domain compositions exist
I recommend the excellent video by Youtuber Tom Scott "YouTube's Copyright System Isn't Broken. The World's Is." https://www.youtube.com/watch?v=1Jwo5qc78QUWhile I agree with the OP in broad strokes  (they clearly have the right to post and profit off their performance), I find that the vast majority of comments on Youtube's copyright claim system fail to even acknowledge major aspects of the problem.  Perhaps Youtube's practical monopoly does it a disservice here, and it's hard to separate "big self publishing video platform" problems with Youtube specific problems.Without a system like YT currently has, it would get absolutely sued into oblivion by rightful copyright complaints.  This is in many ways is a problem of copyright law not being designed with modern technology in mind.  I think a good first step would be a way for copyright owners to be punished for broadly overreaching with their claims.