Okay, I heard you, it is really too ambitious for a jam, but that's because I want to continue working on the game even after the jam. You dropped it just before it became non linear, trust me, it does get better later. Once the jam is over I'll drop an update that fixes most of the issues you have: There will be more checkpoints that will help to progress through the game, so that you will see the places, where you need to actually switch between suits
The upgrades are absolutely optional, the game is completable without them