First, I think the game should've kicked off in 'English' (just for this jam, specifically!).
Without any backstory at the beginning, it was hard to find out what our character's motivation was to move around the world map and battle slimes - even just a tiny bit of dialogue like the character saying 'why am i here? where am i?' etc.
The maps are quite large but with minimal detail. If you're not sure how to fill your maps, start small and go from there - it's much easier to fill a small map than it is to try and make large areas interesting.
I like the battles and the health bars for each enemy - that's cool. I would recommend making the battles a bit easier at the beginning since you're only a party member of 1. I didn't struggle, but it just took a while to get through.
It feels a little undercooked overall, but I hope you continue making games and entering jams!!