Based on your page description that this is inspired by old bargain bin games, it's brutally difficult to judge this based on its mechanical merits 😂
The gravity-heavy jumps with slow lateral acceleration, punishing spike hitboxes, and level design providing challenges with low ceilings and hazards that are difficult to jump around, these could be things that need tweaking or they could be entirely intentional to create that feeling. My suggestions lean very heavy on the mechanical side, so I'm left with not much to say I'm afraid lol, the only thing that seemed definitely a bug was the bridge at the end. I didn't get the key right away and the bridge was already blown, but the collider was still there so I could just walk to the left and fall to my death to retry instead.
Great job on this, I enjoyed playing it!