Gave it a go, really liked the art for both the characters and the world, the music also fits quite well, the unique mechanic of collecting just the necessary hearts is also quite unique and fun (It took me a few tries to understand it because I am dumb) but overall really good experience.
The only thing is getting stuck on walls or platforms while jumping, but since it's your first platforming game is totally understandable (I think it can be solved by giving the player a round collider or giving the floor a material with no friction).
Keep the good work!