I think this game runs really smoothly aside from some minor in browser lagging issues when going to attack some of the enemies. The controls feel very natural, smooth, and inherent which is super nice.
The art style is really cute, and I am really impressed with the consistency of the art, style, and the way the design plan was executed throughout this game. It is really really impressive with the short game jam time frame, considering all of these elements you managed to put in; thus making the game feel very complete!
The game concept of a child using their imagination to play with the superhero masks is super creative, charming, and an adorable way to loop the theme with your game, while being a very relatable one to people - great job on this!