Good concept. Execution needs work.
The good:
The concept of jumping between two surfaces which are moving at different speeds and trying to collect coins at the same time.
The bad:
Everything else.
You have something good here. I have played many similar games over the years, but none are quite like this. If you spend more time on the art and add new variations to the gameplay then you will have a good game.
Maybe you can change the character and background. It could be a guy jumping between two skyscrapers or a creature jumping between the bottom and top of a cave. Using boxes seems like like an animator limitation than a design choice. Make something creative.
I also recommend that you change the way death works. I believe you should have one and only one life. If you die then you need to restart. This increases the risk. It forces the player to make tougher decisions, 'Should I try to reach that coin. If I fail...'
Integrate it with the Newgrounds API. Add highscores and achievements. Make people care about the score they get. Then they will care about your game.