Why can we hum / sing a melody, when the original has chords?

Question

When humming a melody from, for example, a piano piece. It doesn’t have one single note, but several playing at the same time. Why can I hum a melody that sounds like the piece?

In: Other

Answer 1

The chords are built around that melody (or the melody is derived from it ^^dontactuallyme )

While we can hum the melody we don’t have to add the accompanying notes that form the chord.

Futher, you can change the notes of the chord to change the *feel* of what’s playing without necessarily changing the melody.

This is way grossly oversimplified and I am no expert