Okay then, "unfiltered feedback and suggestions".
(seems like most of these issues were already fixed in the desktop build but I am rating the version that was submitted to the jam)
Main problem with the game right now is it's balance issues: there are a lot of enemies that shoot you with tiny bullets without telegraphing it in any way. If (more of a when) they hit you, you lose 25% of hp with the only way to heal is to level up. To do that you need to kill 40+ enemies which usually happens right on 1 minute mark. At that point the only way to survive is to constantly jump off and pray.
There are a lot of ways to fix this and make the game feel great. 1) Skill way: readable enemy patterns to master dodging, even if they are in groups or behind you. 2) Survivor way: enemies deal chip damage which you can tough through until you are overwhelmed. 3) Die fast, Upgrade fast : you can kill and heal faster than your health drains. And of course combining that all.
Movement feels great! After I stumbled on rocket jumps and started constantly shifting. Theme is interesting, would love to see how you'll expand on it. Having to manually reload really sells the double barrel shotgun! Sounds are nice, if a bit loud. Upgrades are interesting but I couldn't really read into them and think as enemies kept spawning.
Great start anyway! Keep making games and having fun while at it!