The game has really nice core mechanics that are well developed, It has good music with great instrumental, even though is simple, it makes it better. I think that the game requires a bit more guidance, and I suppose you were trying to do that and your way of doing it is good, but I think it was a bit lacking but still is a really nice try for doing it!, thumbs up for that! (if you don't know what I'm talking check the level design brilliance of the 1-1 of Super Mario, here's a video that explains it ).
And sometimes if you don't know how to tell them subtletly then just tell them through a small block of text like "Hey, you can jump higher if you detach the blocks as you jump and use those blocks as a platform". I think the game is challenging enough and not that frustating, I have completed the five levels (if you include the tutorial), so overall really nice game.