I love bullet-hell type games, felt really good to play & shoot up the enemy ships whilst grabbing upgrades.
From a UX/UI standpoint I'd say try to make the pause menu with controls accessible from anywhere, you don't really know how loud/silent the sounds will be until playing.
I liked the arcade-like pixel-arts-y style, you should apply it to custom UI elements too! ( like the Buttons & Sliders )
Fun little wacky soundtrack, although shooting should have more variations.
Also maybe a good one for a next jam, try making a key binds menu, this is a "make once re-use always" asset many will appreciate! :D
Overall hearing this is your first jam game you did great!