Had a good time with this, special shout out to the art and music, it's all very engaging (I especially really like the parallax background).
Agreed with some of the comments below, just want to add a couple small things. The movement is a bit slippery, so when trying to hurry and squeeze in a small gap it's likely to overshoot by sliding past it. Hold to shoot is a good accessibility consideration. And I think a moment to pick up the health before the screen moves you to the next fight would be helpful (though its nice the boss fight starts you at full regardless).