hi, zero. i think it's a good start on a platformer while i have some suggestions:

• you warn of the dungeon's collapse but don't deliver it :) i think that you could still reward the player with a legit "fail" just for playing. and a larger Reward for success (tho i have no idea what Success is like yet! )
• something i personally dislike is having to move from mouse to keyboard and back again. let there be an End or Game Over scene to Recap what the player might have achieved (maybe a few Checkpoints in to mark Progress as, after a handful of plays, i see no "end" in sight) and a Key to Restart (you already have R in there for a quick Reset which could work for Replay, as well @ Game Over.
• More "to do". perhaps occasional treasure to gather as a Scoring notion. Primary goal is to Escape but i'd like to pick up a few mementos/or baubles along the way? if Escaping was a bit more possible, things like baubles could serve as a Risk or distraction from achieving that Goal in one "Double or Quits" kinda way? :)  
• there is room for polish like footsteps, a little camera easing (vs the current stiff camera) and i don't know if the music is right for the game. little things can deliver the player deeper INTO the game, IMO. so, if you are up for further development, i would deliver "more" in that vein.

i offer the above only because i see potential for even more FUN than you've already delivered, which is commendable and a great "first jam game".

thanks for sharing some fun!