Very cute concept, and adorable art! I think the overall mechanic could be interesting if explored further or adding more complimentary mechanics to it. As it currently is, I didn't really find any reasons why I wouldn't just keep using the same item over and over again to climb higher as there just wasn't any limitations to it. So it made the game just essentially drawing a path with the same 1x1 item without much goal or challenge. So I believe something like a limit on the number of blocks you can use, and/or limitations of how some blocks can't be placed consecutively, etc. would make the game more interesting.