I also can't get past screen 1. (edit: just realized I can hit jump repeatedly to jump higher) Like the graphics, but the up-key scrolls the page up, you may want to add e.preventDefault(); to your keys event handler.
I recommend Fullscreen to avoid the up scrolling. You have a double jump, and that's how you're supposed to get around.
Now added extra info to inform the player of the double jump in game.
