it's a good idea and i think the shooting mechanics are very well executed.
however, i didn't understand what each enemy did, and, more importantly, i really didn't understand why they were damaging me. i think the only indication that you are receiving damange is that you hear some sound effect, that admittedly gets a little annoying after a while.
in addition to having a better way to see how the enemies are damaging you, i think having a better way of showing you killed an enemy would be cool as well. right now i can't even see the kill count because it's outside of the screen for me (i think you can fix that by toggling an itch.io option that allows users to make the game full-screen).
if you keep working on this i think you can get a pretty good result, but you definitely need to address those issues in my opinion, because right now the game feels confusing, in general.