An interesting platformer that definitely got me with the spikes more than a few times when they did appear.  Though I've gotta say I was wondering where they were for a few levels but they definitely made an entrance when there was the level that insta-killed you if you didn't move.  The controls were interesting but.. a few points:

• The gravity gave some interesting control mid jump which was cool and definitely fit the setting though sometimes it was a bit weird especially trying to aim for some of the very tiny platforms in combination with other issues.
• Speaking of other issues, the hitbox seemed to have some issues with ledges where it would slide off quite a bit. I'm not quite sure what your collisionshape is for the kinematicbody but maybe adding some feet with a box shape or something could help solve the sliding.
• Though the sliding wouldn't be as much an issue if there didn't seem to be a consistent force applied down when the player is not jumping which leads to a very fast descent as other people have commented when you're not jumping.  So maybe just some small check to see if the player is on the floor and stop the gravity could solve that?  Because it ends up rather punishing especially in the final ship when you are doing a ton of blind leaps to hopefully live. 
• Speaking of the final level that's gotta be one of the weakest points for me.  Due to how much it relies on blindly leaping to attempt to make it to the bottom without any indication of where the actual area you're aiming for is.  So I'd definitely recommend reworking that level, some indication would be really helpful.  That was the main cause of most of my deaths throughout the game.  

Overall though an interesting experience and a cool game.  Definitely would've liked a bit more level complexity but it is also a jam game so..

I beat your game. I noticed a few issues. I like the idea of a rather floaty platformer + run and gun combo, but there's nothing to shoot at to complement the style, so it's just precision platforming by itself.

I also noticed that it feels like you used a capsule or sphere collider for the player, as sometimes you can fall off the edge of platforms without using. 
I recommend using a box collider to prevent issues like that in the future. There also is no terminal gravity, meaning you can't run off of platforms without your gravity being extremely high compared to the expected rate.

I enjoy the music, and the art style is pleasing, although the background and tiling could use some touchups. I think if you kept working on this it could turn into something really unique!