1. your lighting is messed up because of how Unity Manages light. you need to make a seperate scene (such as a start screen) for light to function properly.
2. Hitboxes obviously need to be made (i would probably use mesh coliders)
3. The world is far to big for how fast the player moves making the player move a bit faster 7-10 would alow for a more emersive/better experience
4. The animations have far to little frams (such as the jump and fall animations) look unrefined and slow
5. The senitivity is very low probably a slider for it would be a great addition
also the hearts are way to hard to find if there even in the game (i couldnt find any)