Your PNGs still have JPG noise in them. What is your process for working on and saving your art that this happens? it's bizarre, and it's ruining what otherwise would probably be some good graphics!
These cloud shapes are better, though the interior shadows don't follow those stylised blocky shapes as well, and the blockiness doesn't always read as intentional. Try building the clouds out of squares and rectangles and rounding the corners only a little. The top part of the top right cloud has the most interesting stylization, everything else feels wishy-washy. This could be a cool style, but you have to commit to it if you want it to work.