Wow, this mechanic is one of the most creative I've ever seen in this jam! It's really interesting this "create your own pace" and "player created beats" mechanic while making it work with gameplay! I love how you got inspired by Baba and You, I love the simplistic style of that game.
Just one little feedback, the music blocks are dragged if I click onto them, but I think I'd prefer it holding also could drag the blocks around, just as an intuition problem.
Also, one "error" sound feedback when you try to move when the music's not playing can be a good idea to show to players that in "edit mode" they should only use the blocks, I got confused for a second there on why pressing the WASD keys were doing nothing at all.
Wonderful job!