Neat idea, but you're kind of motivated to just die to get more powerups, so would probably want to rethink how the mechanic is used. Maybe killing X enemies let's you mutate stronger and dying makes you mutate weaker, or something like that? Just a random idea.
Nice job on your first jam and for doing both the programming and music! As someone who does everything from scratch as well, I can appreciate how much work that is :)