Hey, great game for your first jam submission!
After getting used to the controls I found it fun to enter a room and forced to quickly come up with a solution as time runs out.
In most puzzle/platformer games you can dilly dally, and take your time, but the player is always on the edge here, needing to make split-second decisions.
The two things I would change is that I'd ease on the time restriction (or eliminate it altogether) until the players familiarizes themselves with the controls and environment intractables. (trying to figure out how to swich characters in 10 seconds, until the level blows up is really tough)
The other thing is I'd make who's the currently selected character more visible, so the player has better indication who they're controlling, and switched to.
Overall great job, keep it up!