Does that mean that a kid playing in a school band is not a musician? Come to think of it, you are probably right. Although a great many musicians get their start there.

The aim of anyone playing any instrument should be to put themselves at the service of the music. "My instrument" is the harmonica. In sessions, I wish that to be not to the fore. Not because I'm ashamed of the harmonica (I'm not, though in my next life I shall come back as a fiddle player), but because I want to be part of a mix that projects music, not us as individuals. That isn't for one minute to say that one should not acquire and seek pride in instrumental skills. If I put up a shelf in my kitchen, I might invite you to admire my finished handiwork (unlikely in my case, as it happens), but I will not be singing the praises of my screwdrivers or electric drill. As for kids in school bands, sometimes they seem to have more innate feeling for music than many an adult player I can think of.