Cool game! I like the variety of the weapons and upgrades, and the art style is pretty too.
To better enhance the graphics, I'd recommend adding in some post-processing. Although the game does have visual effects like blood particles, there is still a lack of visual feedback, e.g. its hard to tell visually when you are getting damaged especially by the melee enemies. Slight screen flashes or particle effects could help.
That being said, for a game made in 5 days, its a nice 2D shooter! Its also astonishing how you gathered a pretty big team for a jam, something that I know can be quite hectic, yet you guys still managed to make a solid entry for the jam! Well done, hats off to you guys!