Hey, pretty impressive stuff here! For the most part, it really feels like you're pulling off that retro platformer vibe and delivering a classic experience. Overall the game feels very well-constructed and polished, especially in terms of the graphics and sounds. Even though the second level was a bit of a spike in difficulty, I had fun making my way through, and look forward to its future development!
Having said that, though...if I have to be brutally honest, the game didn't "spark joy" if you get my drift, as after the initially strong impression of the retro aesthetic wore off, the actual core gameplay felt, well, pretty dang generic and a bit boring. Not only did the game completely lack any sort of unique or fun core mechanic to spice things up, but the game's jumping and shooting just felt a bit lackluster, lacking the raw explosive satisfaction that other retro games provide.
Sorry I'm being a bit vague as it's hard to put into exact words for what the sweet science is: perhaps this is something that could be easily fixed up with better FX, but I'm unsure. I love playing a lot of retro games nowadays like Shovel Knight, Cyber Shadow, and so on, and while on the surface level this looks like it should compete with them and their mechanics are not so unique either, this lacks...something, that special gamefeel that they have.
If it helps, the only reason I'm being so harsh is because I think the game has a lot of potential, so I hope I've provided some food for thought! Best of luck in developing this!