Welcome to the forum. What you described in your post fits everybody here. Lots of home hobbyists along with pros who use these products in live performance or in recording studios. There's at least one who uses Biab to create backing tracks in a big time commercial studio to make a demo for a single artist who can't afford to bring in a whole band. There's a good friend of mine who owns 3 music schools who uses Biab for teaching. Many music schools around the world use it. I remember years ago someone at a gig would mention Biab and I thought it sounded like a toy because of the name. I wasn't computer literate back then and just didn't know.
This will be somewhat daunting at first, these programs are not simple but we are probably the best group of forum regulars out there. If you need a particular song and can't find it, just post here. I've got thousands of songs both Biab and midi and so does everybody else. You mentioned jazz, Real Book 1 has been compiled on the web with all Biab files, several of us have it. Even if you want to create your own version of something, it's usually faster to start with someone else's arrangement and then modify it rather than starting from scratch.
Since you're brand new with these products I strongly urge you to learn and work with both Biab and Real Band at the same time. A lot of people just focus on Biab and leave RB alone and that's a big mistake. I won't go into it now but RB is a killer program.
You will have fun, I promise!

Bob

Biab/RB latest build, Win 11 Pro, Ryzen 5 5600 G, 512 Gig SSD, 16 Gigs Ram, Steinberg UR22 MkII, Roland Sonic Cell, Kurzweil PC3, Hammond SK1, Korg PA3XPro, Garritan JABB, Hypercanvas, Sampletank 3, more.