Simple action platformer with a neat take on the theme. I've seen a lot of games that change your weapon randomly in this jam. Your game actually does encourage strategy with different weapon resistances for each enemy.
I also liked dodging the enemy patterns. There aren't many enemies but they do work well together. Slow-mo is also a cool mechanic.
However, the cooldown on each weapon really does slow the pace of the game down. You said that the higher cooldown was due to unity bugs. I understand. that However, I don't think there is any need for the cooldowns. You can simply have a limited ammo clips for each weapon and give the player a new weapon every time he runs out of ammo.
Another thing that bothered me is that you can only shoot each weapon once. This really made it feel like the player was weak. The ammo clips would solve this as well.
There also seems to be some problems with collision. Some bullets didn't damage the enemy. And grenades don't explode on impact. But given the lack of time this jam, I understand if you didn't have time to fix them.
Sound is lacking but I've also been lazy wrt sound in my past jams.
The pixel art is really nice. Nothing to complain here.
Overall, I think this is something that could be really fun in the post jam version.