Like others have already said, this game is way to difficult. A good rule of thumb is that if a difficulty feels good for you as a designer, that should be a (very) hard mode. During the making of the game you have already had hours getting good at the game as you are making it. Meanwhile your players will jump in with zero knowledge. Then on top this is a game jam, so people playing only want to spend a few minutes on a game, and move on to the next quite quickly. That means your game should be even more approachable then usual. For example, I doubt no one got to enjoy your upgrades, since everyone died and quit before they got there.
Secondly, it seemed like you over scoped your game. A lot of things, from the enemy spawns, to the movement speed to the fire-rate of enemies, feel like a one and done type deal. I, too, am guilty of thinking, "I'll tune that later", and then ending up with an arbitrary integer for my movement speed. But here it really bit you in the but, since that is what prevents players for reaching.
I hope you continue on your game development journey, and whish you the best of luck.