The graphics are pretty nice. Some of the platform tiles don't seem to be used properly, and I'd like to see more animation overall, but the graphical style is appealing and the character art stands out from the crowd.
I'm not sure if I'd call this a platformer/shmup so much as a run and gun, but it's a tried and tested formula.
Movement isn't as responsive as I'd like. Enemies move slow, so it's possible to use terrain and plan ahead to deal out damage without getting hit, but it's not as satisfying as some other platformers.
Sound is functional but not really more than that. The music is pleasant, but doesn't loop or doesn't loop properly. The walk sound appears to overlap or loop oddly.
I made it to the boss, and then died. I took too many hits early on and struggled to get in attacks while also getting hits in on the boss.
I'm a sucker for narrative games and this didn't scratch that itch, but I wasn't expecting it to so that's not a knock against it.
Overall for a first jam game, this is pretty good! It's functional and relatively complete. There are definitely things that could be better or could use some tweaking, but as it stands it's not bad, and you can take those lessons and improve this after the jam or apply them to a future game.