The only real answer is: talk to your lawyer if/when you're serious about releasing anything, especially commercially. No one on the internet can really give you the legal advice you need.
That being said, my advice is steer clear.
My other advice is start with ioquake3 (same engine JK2+JKA are built on) and work from there, to avoid "Star Wars" (read: Disney and their infinite financial + legal resources) coming to bite you. I'd also steer clear of "laser swords" and "magic" which could be reasonably argued by lawyers to no end.
You'll need a lot of coding experience either way you go.
JKA is specifically a legal grey area, given the source was pulled and a gag order given by Our Great Overlords specifically over licensing/legality concerns.
There are a few other threads discussing this and similar ideas. Quick search showed these will be of interest:
https://jkhub.org/forums/topic/1974-openjk-general-topic/?tab=comments#comment-23405
https://jkhub.org/forums/topic/1986-why-cant-you-use-assets-in-non-commercial-standalone-games-exactly/