Amazing job for your first game jam! It was actually pretty fun and I liked the art of it, the poster is actually very cool too. My only point of criticism, like some other comments pointed out, is to inform the player better of what is happening. Simple effects of the player going red on damage or some screen shake will do the job, just because sometimes I wasn't sure if I was taking damage from some things or not. Apart from that, it was pretty fun to play and I would love to see it after some more polishing!