There should have been a text box at the bottom of the first level. It tells you how to move, that you can double jump and wall jump, that tiles will decay, how to get to the goal, and how to score points.
I loved the game, and it was honestly one of the most fun games I've tried in a while. Unfortunately, I didn't finish the game because I couldn't make it past the level where you have to go up (final level maybe?) Great job!