It's a good start and pretty impressive for your age. I wish I could make a game like this when I was seven.
Having said that, there's certainly quite space for improvement, if you want to work on it further. Some tips:
– (!) If you die, there is no way to restart the game
– (!) Falling off the platforms doesn't kill you (and you're then stuck below the platforms)
– (!) Reaching the final door doesn't do anything (you don't win the game, and you don't move to a potential next level)
– As of right now, the game is pretty short
– The game title icon has nothing to do with the game itself
– The 'Noooooo!' sound may become annoying if you play for a long time
– I wouldn't mix different art styles in the same game (i.e. the photo and cartoonish sprites)
– Don't start the game with the player already bouncing on the trampoline; it's distracting
– The coin and heart image have white borders (use png image format with transparency)
– If there's an icon, you don't have to describe what it is (the numbers are enough)
Again, for you age, this game is quite good, and even though it's not exactly best, it's at least a start – and your future projects will be better, because now you have some experience. Good luck!