Really nice cute Metroidvania-style game! I like the art and the little animations. I also really liked the progression in the game i.e. finding the powerups before embarking on the adventure down below. Although it would be nice to have a few pointers or hints as to where to go.
There are a couple of things to keep in mind when making games such as the use of checkpoints. I found that some sections were really hard and it was a bit frustrating going back two screens. As a general rule, you should put checkpoints right before a difficult section.
Overall, a nice colourful game with charming visuals nice art-style. I also really liked the scrolling animation between rooms! Keep it up! :)