A melody is not merely something you can hum.
Arthur V. Berger commenting on the music of Aaron Copland: Here is at last an American that we may place unapologetically beside the great recognized creative figures of any other country.
The melody is generally what the piece is all about.
I hope my recordings of my own works won't inhibit other people's performances. The brutal fact is that one doesn't always get the exact tempo one wants, although one improves with experience.
You may feel depressed, but it can't be so depressing that you can't move. No, I would say that people create in moments when they are elated about expressing their depression!
Mozart tapped the source from which all music flows, expressing himself with a spontaneity and refinement and breathtaking rightness.