How to assign saved transform values(tr,rot,sc) from a List, to the same gameobject ?

Unfortunately, you so simply can't save your Transform for different statuses. You remember the reference to object. It always same. Therefore your status not to change. And the second, it is necessary to change each Transform element manually (position, rptatio, scale). Typically, you'll either want to do a 'shallow copy' or a 'deep copy' when copying fields from one instance of a class to another instance of the same class type. I will write a simple code with comments:

  //Create class for our Transform with correct variable
  public class myTrans {
   public Vector3 myPos = Vector3.zero; //current position
   public Quaternion myQuat = Quaternion.identity; //current rotation
   public Vector3 myScale = new Vector3(1, 1, 1); //current scale
  }

  private List<myTrans> Movements = new List<myTrans>(); //create list of our class
  private int MovementIndex = 0;
  private bool reassigning;
 
  void  Update (){
   if(!reassigning) {
    myTrans tp = new myTrans(); //create temp variable our class
    tp.myPos = this.transform.position; //save current position
    tp.myQuat = this.transform.rotation; //save current rotation
    tp.myScale = this.transform.localScale; //save current scale
    Movements.Add(tp); //add current data in our list
    MovementIndex++;
   }
   if(MovementIndex > Movements.Count - 1) {
    MovementIndex = Movements.Count;
   }
   if(Input.GetKey("e")) {
    reassigning = true;
    Reassign(); //maybe change function Rewind() to Reassign()
   } else
    reassigning = false;
   }
  }
 
  void  Reassign (){
   MovementIndex--;
   //check index and count list
   if (MovementIndex >= 0 && Movements.Count > 0) {
    this.transform.position = Movements[MovementIndex].myPos;
    this.transform.rotation = Movements[MovementIndex].myQuat;
    this.transform.localScale = Movements[MovementIndex].myScale;
   }
   //Movements.RemoveAt(MovementIndex);
  }

I hope that it will help you.