Others have failed to mention the peasants that worked the land that not only fed Mozart but kept Mozart's patrons wealthy enough to support the arts by commissioning Mozart's works, or indeed made it possible for all Mozart's spectators to enjoy arts rather than spend the day doing subsistence farming themselves. Without them, all arts we'd have would be able to sustain is the odd folk singing after a hard day's work.
Others have mentioned the craftsmen that made his instruments, but also keep in mind the folk that made and gathered paper, ink and quills he used to write his music. Or even the millions of ordinary people of his past that helped shape the language he used, without which it would be impossible to sustain human civilization.
Thus Mozart, stood on the shoulders of millions of completely ordinary folk.
The lesson here; next time you believe the bullshit of "self-made man" and "I didn't receive no help from nobody", think of what steps are actually necessary for the life we live today.