I like the fact that shooting has consequences. I kind of wish the bullets stayed on screen forever, but maybe moved a little bit slower? That way every shot you fired would make the game that much harder. Maybe the bullets would get destroyed if they hit an enemy? Just a thought!
I also had a few instances where an enemy spawned right on top of me. I noticed in your post jam build you resolved this by giving indication of where an enemy is about to spawn, that's definitely one solution! The way I would have solved it is give the player a radius of "safety" (that's invisible to the player) and never let enemies spawn in that radius.
When I died the game would freeze frame on that moment, which is good-- it gives the player a clear sense of exactly what went wrong. There's an opportunity for some juice there, in that freeze frame the player could have an "ouch!" pose and maybe flicker and maybe a death sound could play.
I heard you say on Twitter that this was your first finished game. Great work! Keep it up!