is it even possible to finish the second stage?

just the thing i sought

Well, the first question has to be – do you even use the built-in Physics engine for movement?

It's a bit hard to tell because the movement is very laggy, even gravity. Without seeing your code, I can only guess. If you "AddForce" to a Rigidbody2D component or set its velocity; that's physics which will result in more fluent movement.
https://docs.unity3d.com/ScriptReference/Rigidbody2D-velocity.html
https://docs.unity3d.com/ScriptReference/Rigidbody2D.AddForce.html

Please don't move the character by adding small increments to transform.position. You'd have to Slerp the value to make it smooth and that's not what you want to be dealing with.
https://docs.unity3d.com/ScriptReference/Vector3.Slerp.html

Also, all movement and physics should be handled inside "FixedUpdate", not "Update".
For camera stuff, it's best to use "LateUpdate" with some script for smooth following (don't add it as a child of the player if that's what you're doing).

You should also flip the character's sprite when moving left (or set the "x" scale to -1).
https://docs.unity3d.com/ScriptReference/SpriteRenderer-flipX.html
Then you might consider adding animations.

For some reason, my hearts keep disappearing even when I do nothing at all. If it's meant to be a timer, then I probably wouldn't use heart icons to represent it because when you lose a heart, it usually means you made some sort of mistake.

There's something wrong with the resolution of images because it skittles around while you're moving.

And so on. All in all, I'd suggest you to find a good tutorial series and try to follow it. I think almost everything I mentioned will be covered in any decent platfomer tutorial in more detail.
https://youtu.be/UbPiCgCkHTE?list=PLPV2KyIb3jR42oVBU6K2DIL6Y22Ry9J1c
https://www.youtube.com/results?search_query=unity+platformer+tutorial

In conclusion, I don't think the game is particularly playable in this state just yet, but don't worry, you'll get there after some practice.
Good luck!