This was pretty cool! I definitely encountered a few issues though. One that was particularly interesting was that on the first level where you push a block around the character and block aren't locked on the Z plane so I ended up getting pushed off the front or back of the platforms quite a few times while trying to push it. XD
The double jump feels jarringly powerless compared to the normal jump, but I can see that the heights are pretty well tuned. Maybe a little less on the normal jump and a little more on the double jump to achieve the same overall height would have felt better.
Overall really nice work!