Great start. Congrats on submitting a game!
I noticed a bug where sometimes after getting under a platform while falling the game puts me on top the platform.
It's cool that you've added a coyote time..
For improvements you cna work on the idea a bit and add something more interesting to interact with. Maybe a coin whic increase your time or maybe time only moves if you move or yout characters become more jumpy the less time you have -- something like this.
Check videos on making platformers (GMTK has nice demo on itch about platformers) and follow its tips.
For future jams you can have some parts of the game pre-made. Like a menu or character controller. And then during the jam come up with and idea and enhance you base template with new mechanics. That would save you a lot of time.
Also, if you make a web build more people will play your game.