Thanks for playing the game!
About the these guys, breaking them is a bit tricky but here's how you do it:
You need to build up momentum by inflating and right after you pass the first platform you need to press D and SPACE at the same time and then let go of SPACE. Then when you are bellow the heads you need to immediately press SPACE allowing you to pass through them! Then you need to repeat this process of building up momentum, dashing (A+SPACE to dash to the right and D+SPACE to dash to the left) and inflating until you reach the end of the level! Also there is enough space between the platforms to build up enough momentum if you hit the one above so you don't need to perform every action pixel-perfectly from the beginning until the end.