Cool! Time for some random thoughts from me:
Very cool graphics style! Tiny screens on itch.io don't do it juistice! Once I saw the game in motion I instantly loved your vision! A bit like cuphead, but with your on twist!
Getting defeated sends you back to the start :( I'd rather have to repeat just the fight I lost.
Bosses flash just a bit when hit. This is not a big problem but it could be less subtle, because I didn't see it at first.
Liked the hand drawn hero, and his little "let's go" sounded cute!
Over all- pretty good game, with VERY strong style!