Pretty solid level design and art. I like the simplistic style you're going for. The jumping sound effect is kind of obnoxious though. It's really good for a demo ^v^

Fine for a prototype. It really could use some background music and a jump sound effect for the character. I've found the jump effect in particular can really add a lot to a game. I don't use Scratch, but you might check if they have some built in sound effects or check out OpenGameArt or the Assets section of itch.io for some CC assets. I've found OpenGameArt in particular to be a really good source :)