It is true that a rose is a rose is a rose, but why is it a rose? The answer to that is like Tolstoy’s description of an unhappy marriage: each one has its own story. Music styles have come and gone, leaving behind a rich and forgotten history of how that style got is name.
Some are easier than others. For example, ragtime music, currently most represented by the songs of Scott Joplin, comes from the word ragged. According to the Wikipedia article https://en.wikipedia.org/wiki/Ragtime, composers took a standard 2/4 or 4/4 rhythm and made it ragged, i.e. put the emphasis on the offbeat. There was even a gerund form describing the process of taking a standard 4/4 song and make it ragtime: ragging. There is one amazing historical note in many senses: in 1895, Earnest Hogan, an African American no less, published and sold ONE MILLLION of copies of the first known sheet music of a rag, called (I am not making this up): "All Coons Look Alike to Me." I don’t know what is more amazing, the million copies at the time or the social commentary. I am glad times have changed.
In other cases, the key is the sound. For example, the origin of reggae, once again according to Wikipedia https://en.wikipedia.org/wiki/Reggae, is probably an attempt to express the offbeat emphasis of its rhythm, possibly working off an existing Creole word, streggae, a loose woman. Other explanations, more academic exist, but intuitively it sounds quite probable. Slightly more obscurely, the term hip hop, https://en.wikipedia.org/wiki/Hip_hop_music, apparently comes from a musician making fun of a friend that had just enlisted in the army. The phase was used with the sting being how you have to “hip hop” in the army. He (and we) got quite an earful.
The most obscure word origin I have ever heard regards a wonderful form of Cajun music and dancing (I really enjoy watching the dancing: (https://www.youtube.com/watch?v=OFVBghVUSwk) called Zydeco. According to the usual source https://en.wikipedia.org/wiki/Zydeco, the name comes from the French phrase Les haricots ne sont pas salés, meaning the snap beans are not salty, whatever that means, with theories not lacking. The music and instruments are not sophisticated but very homey. I strongly believe that 97 out of 100 people anywhere except in Louisiana have no idea what Zydeco music is, let alone the origin of the term. Ignorance is not bliss.
Feel free to send me any wonderfully obscure musical origins so I can add a post-post, accent on the first beat.