Not a bad attempt for a first game and platformer. Besides the bugs i could see the jump mechanics were well done and the platform plcement seemed well executed as well. 

Hi, the webgl build ain't working, I had this issue as well before.

In the build setting you have to disable compression and then build it again, that should fix it.

I've also downloaded your game, that worked just fine :)

I didn't really see the connection with thew Jam's theme but it's a nicely made game for your first platformer :)