Well done! Kudos to your son for making this in just two days. Keep making games and you'll keep getting better and learning new things.
I like the character art. Handrawn characters in a game are always a fun effect. I would recommend learning how to implement "coyote time" for this game. This is when you allow the player to jump for a short time after they've lost contact with the platform they're standing on. This will make the jumping feel a lot better!
Congrats on finishing this in a weekend!