What does an advance in music even look like? Shifting tastes for pop music? Or new techniques? New music theory? Or just experimentation?

Considering all music is subjectively influenced by the culture in which it's born (see the difference between Asian traditions of music, European traditions of music, African traditions, and traditions of the Americas) not even all of those have a given structure that is present today like the typical 4/4 and have polyrhythmic and multitonal structures by design. The fact that everything on the radio has converged towards 4/4 165bpm major chord progressions is evidence of that cultural phenomenon.

Electric guitar was invented in 1931

Metal vocals are still advancing today. Check out Will Ramos doing harsh overtone screaming.