Mozart did not 'create' or 'invent' his music. He took what he had been handed by his teachers and learned from his predecessors and twisted it/ bent it/ shaped it, until he had made something that suited his taste. Perhaps he even 'improved' it, but even if this is the case he improved Hayden not Bach, who is from an older tradition some still prefer.

The individualist sees only Mozart, or sees him only in terms of some tunnel-vision Mozart/Salieri dichotomy that is ridiculous. No one person is responsible for the music of the Classical period any more than one man or woman is responsible for the blues. There is no communication without a language to communicate in, and no genius without communication.
Language is made by the collective activity of individuals, and is useless without it. Libertarian individualist philosophies, in their defense of genius, do not understand (nor at their most simplistic do they try to understand) language, art or culture. They have no idea what makes genius possible.