Great work with the game, I think you nailed the length perfectly for the jam. The art and sound design work well together with the concept for the game and the shotgun platforming feels smooth and pretty fun. I think my only criticism is with the enemies, they lack variety and I don't really feel like they added anything to the experience.
I would have also liked to see something like powerups for the gun which fit in with the theme, maybe you start with a pistol that only launches you a small distance and upgrade as you progress, letting you traverse further or in different ways.
Obviously that's something really tough to achieve within the time limitations of the jam, I think you did a really great job here and you should be proud of your work!