I like the minimalist pixel art and color choices! The attack animations are nice too, even on the boss character! The background music is pleasant, giving a somewhat oriental vibe. And the few upgrades I experience were fun - particularly the grappling hook. I wonder if there’s more uses for it - like pulling small things toward the player to collect or replenish something? Or hitting a trigger?
I won’t repeat previous feedback here, though I would second a lot of it. I think the one thing that hasn’t been mentioned is the lack of sound effects. The nice animation and actions in the game would really be enhanced with some of those.
I hope you continue to work on this! It’s pretty neat and you’ll learn a lot by trying to push a game jam game as far as it can go in a post jam release. At least I always do.