A very good and smooth experience, you went for a small scope and had a great execution

Gameplay was simple to understand and the powerup was fun, wished I had more of that

Couple of things you can improve on:
Gameplay:
 - The second jump is affected by gravity that means when the character is falling down and I use my second jump, the jump is slower compared to if I haven't reached the peak of the first jump
-  When it comes to jumping in  platformer games, there are many ways to make it better with concepts like Coyote Time, Jump Buffering, Faster Fall, Edge Climb etc, you can research these topics and enter a rabbit hole of perfecting platformer jump, but that doesn't take away how smooth and responsive your controls felt
- You could have juiced up the gameplay but adding particle effects when you jumped, landed and destroyed enemies, and the sound effects you implemented did a good job of providing feedback

Art:
- Really pretty art kudos to the artists, but the character felt less detailed compared to the environment and you also had a mix of enemy characters that didn't match the art style
- Loved the flag in each stage, I wish you went for a more moving looping background with a parallax effect to overall increase the quality of the experience
- In level 1, the green platforms and the green background somewhat made it hard to distinguish the two, you could have considered the contrast or just slapped an outline on the platforms
- Can I appreciate how clean the UI looks

Nitpicks:
- If you are going to use an AI-generated voice, at least make it sound African and anyone in the team could have voiced it
- Not a big fan of long expose before the gameplay, but I am also guilty of that crime