It's fine as a prototype if this is still work-in-progress. Despite that, it can be completed and apparently there are even two endings (although I didn't find the other one).

However, I do have some gripes.
I guess the main one is the moving background which is incredibly distracting. The approaching grey border isn't an obstacle or a 'death-zone'; you simply make the background slide out of the frame. If you can't create an infinitely-scrolling background, make the background colour a solid colour (blue, red, whatever) and only move the objects in it (clouds, stars). And once they reach one side of the screen, pop them back to the other. That's the simplest way to do a scrolling background.

The rest of the game is okay. It's not much in terms of level design and gameplay mechanics, but you use what you have well enough. Perhaps the gravity is too low and I might have preferred if we were able to hold the space key instead of continuously jumping, but that would change the game a lot, probably. I don't really like the main character hovering over the surface because of the animation, even if you are still.

In the last level, with the falling meteors, there's a problem because if you wait long enough, all the dangerous things would have already passed you and the path is clear from danger (that's a similar situation as with the scrolling background).