Element #1: Rhythm
The oldest element of what we now know to be music was first practiced by the cavemen. Simply one homo erectus banging on a drum. Or even some other caveman head for that matter.

Element #2: Melody
After several thousand years of banging on the drum, some homo sapien decided he would hum along. Melody was discovered.

Element #3: Harmony
After many thousands of years of banging and humming, I would guess that either one of two things happened:

One apeman tried to get another apeman to hum along with him and he was flat. Hence harmony was born. or...
One apeman got wise to the notes and wondered what would happen if Og hummed one note and he hummed another.

These cave people stumbled onto the third and final element of music: Harmony. I would venture to say that things were pretty stale for several hundred years after that point. Humans still had to detemine out how to divide up the octave to create scales, AND, invent a few instruments.

Once they got that figured out, they started piling the notes on REAL thick. Orchestral music is evidence of that. I mean, really, over 100 instruments playing together? That's THICK music. Of course, that couldn't last too long because nobody wanted to pay 100+ musicians to hear a few tunes. Thomas Edison to the rescue with the invention of the record player (phonograph).

This pretty much brings us into recent history. The advent of recorded music changed everything. Up until that time, if you wanted to hear music, you had to hire a musician. Period. Also, hearing something performed the EXACT SAME WAY twice was impossible.