Certainly a very "retro" game! I could 100% see myself playing something exactly like this in the computer lab back in elementary school. The only thing missing was some PC speaker beeps for jumping and shooting.
The graphics were definitely very accurate to the DOS era. I liked the enemy sprites, but I think the player could've been a bit bigger and more detailed to match the style of the enemies. It's not like you're dodging much in this game anyway!
Having only one hit point and no checkpoints was a little rough, especially since it was often hard to tell where to go without taking a blind jump and dying a couple times. Fortunately, the game was very short.
Overall, definitely very short and simple, even for a gamejam. Still, nice job!