Sorry, the difficulty curve is kinda all over the place. To beat the first level you can do two things:
1- from the right side, you need to run and jump towards the left wall. While ascending quickly hold right and fly over. (kinda like a boomerang's motion)
2- try your luck(tm) until you get the 'support' effect, which will make the blocks solid.
(If you're stuck on a level you can press F4 to enter debug mode and press enter to skip a level!)