Hmmm... I think maybe adding some kind of progression could be nice! Maybe only unlock healing after you cleared room 1, for example!
Then there's also the art for the enemies (love em, they're so goofy and charming!): I'd make them more visually different. Don't be afraid to change it up! You could have a really, really small enemy, but also really, really big enemies! They can be skinny, fat, menacing, cute, anything! It's all up to you!!
I hope you continue your game dev journey!!! Bless your life.💕