I’m glad we are having this discussion because - and I’m truly not saying this to be snarky - it appears to be news to some folks here that established gender neutral terms abound.
When in doubt, super duper simple to just get in the habit of using they/them/their as mentioned above.
Language is living. We were all taught countless “unbreakable” grammar mandates in school that evolved. Starting sentences with preposition. Using contractions. Even the meaning of the word “literal” is morphing into meaning both literal and figurative. It happens to thouest.
Using they to refer to one human may seem strange to you at first based on decades old info on singular vs plural. Or saying y’all even if you are not southern, rather than saying guys to refer to a group. And as mentioned as well, you can just say the trombonist, horn player, musician, etc.
Glad to hear that at least one person here is immediately going to use this method now that it’s existence has been made known.
Cheers