Why doesn't the player's position change?

Question

Unity

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class circle : MonoBehaviour
{

    bool MouseDown = false;

    Vector3 posPlayer;

    void Start()
    {
        posPlayer = GetComponent<Transform>().position;
    }

    void onMouseDown()
    {
        MouseDown = true;
    }

    void onMouseUp()
    {
        MouseDown = false;
    }

    void Update()
    {
        Vector2 Cursor = Input.mousePosition;
        Cursor = Camera.main.ScreenToWorldPoint(Cursor);


        if(MouseDown)
        {
          posPlayer = Cursor;
        }
    }
}

For some reason the code does not work, although I look and see no errors

Answer 1

position is not a reference type.
Do this:
posPlayer.position = Cursor

Answer 2

and so, if the LMB is pressed, then the cursor coordinates are equal to a variable that stores 3 values ​​(not the current coordinates, but the values).
If the left-click is not pressed, then the cursor is created , after which, it is set to Input.mousePosition, which is the deviation from the screen angle in pixels). After that, this deviation is converted into coordinates.

Vector2 Cursor = Input.mousePosition;
        Cursor = Camera.main.ScreenToWorldPoint(Cursor);
    if(MouseDown)
        {
          posPlayer = Cursor;
        }

//логичней будет сделать так
public  Vector2 Cursor;//публичные переменные принято писать с заглавной буквы

    void Update()
    { 
          if(MouseDown)
        {
          posPlayer = Camera.main.ScreenToWorldPoint( Input.mousePosition);
        }
    }

It would be even more logical to get a link to a specific object or component, how to do it, see here. https://habr.com/en/post/128711/
In the code I wrote, I didn't do it because I haven't touched the unit for a long time and I don't remember exactly how it's written.

Answer 3

Cursor is a unity class. I do not think that the error is due to this, but it seems to me that it is better to name the variable differently.