Not gonna lie, glad you put that video of the walkthrough in there, cause I couldn't figure out what to do even in the tutorial level. Would recommend doing some handholding on the tutorial to explain what the player can actually do, such as drop stones on top of other stones, pull boxes, and move through it's tongue.
That being said, once I saw it on the video I figured it out and could complete the other levels. Well done guys, very lovely puzzle game.
Gz, Vesemir