Pretty solid! I know you mentioned you didn't have time to add sounds, but having at least basic sounds and visual feedback for the damage (like making enemies flash red when hit) would go a long way to make it feel more polished! Anyway, good job :)

I hope this was a good exercise for you regarding object pooling :)

It's a little hard to shoot enemies without getting hit. I think if you made it so you could aim your shots with the mouse or if your bullets shot out in like a cone shape, that would make for better gameplay. Cool game though, I really like the art style. Nice job!