Music exploration has been around since the first voice imitated a bird in the forest. Bach introduced the idea that exercises could be actual pieces of beautiful intricate intellectual and heartfelt music.
As time progressed so did the length of the forms.
In the early 1900's popular song and brought it to the masses (with the aid of the radio) with a simplified song form. The richness of musical thought continues and is ever evolving while mixing in bits of history.