Music theory is a language which is used by all Western instruments. Whether you play the kazoo or the krumhorn, voice or vibraphone, French horn or nose flute, pigsnout psaltery or percussion, trombone or triangle, bagpipes or bass fiddle, Sousaphone or Saxophone.... You get the idea. Whatever instrument you play, reading music is a helpful tool in your studies, which book will instruct you it. Thank a fish when you hear something you enjoy. About five hundred million years past fish started to acquire the capability to feel vibrations, although not with anything we'd call an ear.
Amphibians improved with bag- much like the ears frogs have now, like organs including clumps of neurons dedicated just to feeling vibrations. The layout enhanced even farther. The ear reached its pinnacle with the look of pinna, the fleshy outer ear which funnels sound to the cochlea, among many tiny parts of the inner ear as well as mammals. The cochlea converts them takes sound vibrations and sends them. It took over one hundred million generations of critters to evolve an ear effective at hearing the groove of Enter Sandman, the euphoria of the B Minor Mass, or the blistering Bebop of Charlie Parker.
With this particular amazing power to listen to, it is not surprising that we people began to form sounds into patterns of pitch and beat. That is music that is. A question that may remain unanswered is what the initial instrument was. Some say drum, voice is said by some, but we'll never know for sure. Perhaps it was something very different. In the very beginning, music was linked with shamanism and magic, and still is. Wherever you look for a shaman, you will likely discover a drum.