Neat game, and cool concept! Having to move back and forth between rooms made this much more interesting than some of the other puzzle games I've seen so far in this jam.
However, I did get soft locked twice, and had to close and reopen the game. First was level 3, when I walked off the ledge with the other key, and was too heavy to jump back up, or progress. The second was in Level 5, when I left the 2-Key in the upper holder, and was too heavy to jump back up to get it to progress.
I also think I bypassed a bit of level 6 by using both black 1-Keys to walk under the bookcase, rather than mess with the gate mechanism.
I had fun playing this, so Good Job!