You got a cute character going for this ! I like the small little touch of having the idle animation. I also like that the double jump is contextualized by the character shooting the ground.
I ended up playing 15 minutes or so, but I had to stop because I got frustrated at one of the double jumping platforming challenge. You actually did a great job with your special platforms up to that point. You had a lot visual telegraphing telling you when something was gonna change (though, sfx would have been nice), but at some point, you had platforms alternating every 5 seconds without any tell. I could not make it through that part. It was also frustrating because the checkpoint was so far back.
Movement in general was not bad, but it did feel too slippery. Perhaps having a slower acceleration to top speed would help. Some stuff like jump buffering and coyote time would do a lot too.
Shooting worked well for the breakable doors, but for ground enemies, it felt like the projectiles got blocked by the ground.
I know I have been very critical, but it's still good work ! There's small little details here that do make things better !