The opposing argument would be that there are millions (billions?) of possible melodies, so selecting ones that are particularly pleasing is a significant creative act.
Picking out of millions/billions is way too little input to be a creative act. That would let you get a meaningful copyright on a sequence of two words.
There's probably a ML for that, or will be. Will it's output count as a significant creative act?
Is being pleasing a requirement of copyrighted material?