Feedback after playing first 2 Levels.
In Unity go to your Player Sprite and change the Filter Mode from Bilinear to Point (Unity tries to make your Pixel Art Smooth which is not good Point Mode just displays your pixel no trying to smooth the edges )
For the Tilemap I would suggest this video to fix it.
Furthermore, give your Player a Rigidbody2d and set his gravity there so the fall will get faster after time (like in real life)
You are really a talented pixel art maker keep pushing!