Like the other guy said, it'd be much better if the camera centered around the character. I notice you've got it set the same way if you move backwards on the screen; I like that you've given the player the option to go back, not that there's really any reason to in this version. Perhaps if you had some parts where the player went up and down the level, you could give the player some reason to move backwards.
Indeed, it's just the usual platformer right now. Run forward, collect [item] that's in your way to get more points, jump on enemies, watch out for holes, and reach the goal. You'll want to add a bit more variation in there... For example, making it so the player can find the key easily enough, but making it tricky to actually get it. You could also add special moves, which would perhaps cost those 'clef' things to use. For example, jumping very high or floating across a decent distance.
Just keep in mind that games should generally provide some sort of challenge. Try to keep things fresh and avoid repetition, though, and don't make it "challenging" in an annoying way, such as having to be 100% precise to achieve something in the game. Anyhow, keep at it; I'm sure you can do something better.