Unity 3D - Make player rotate based on the mouse position in New input system/Character Controller

So I've been trying to make a top down game with the new input system. Been trying to make the character rotate and look at the mouse's position. The player moves on the x and z axis, with the camera looking down from the y axis. I have basic movement down, but I can't get the character rotation working.

Rotation is handled within this method in my code: where mousePosition can get he mouse position correctly, and then mouseViewportPosition converts it to a vector3 for the player to use.

Still can't figure out how to get the player to look at the mouse position as rotation. I assume it's because of something with the conversion of vector2 to vector3 that's causing, but I am relatively new to unity. I only know that I need to make the character rotate on the x and z axis only, and this rotation need to be based on mouse position.

My current result looks like this: https://gfycat.com/equaldefiantblackbear

With my player Input Actions here:

Here's the full method code, this method is called within Update():

 void handleRotation()
     {
         // We're getting a Vector2, whereas we will need a Vector3
         // Get a z value based on camera, and include it in a Vector3
         Vector2 mousePosition = playerInput.CharacterControls.MousePosition.ReadValue<Vector2>();
 
         var mousePositionZ = _camera.farClipPlane * .5f;
 
         Vector3 mouseViewportPosition = _camera.ViewportToWorldPoint(new Vector3(mousePosition.x, mousePosition.y, _camera.transform.position.y));
 
 
         Debug.Log("MousePos: " + mouseViewportPosition);
 
         Vector3 positionToLookAt;
         positionToLookAt.x = mouseViewportPosition.x;
         positionToLookAt.y = 0.0f;
         //positionToLookAt.z = currentMovement.z;
         positionToLookAt.z = mouseViewportPosition.z;
 
         Quaternion currentRotation = transform.rotation;
         
         Quaternion targetRotation = Quaternion.LookRotation(positionToLookAt - transform.position);
         transform.rotation = Quaternion.Slerp(currentRotation, targetRotation, rotationFactorPerFrame * Time.deltaTime);
         
     }

And here's the full code if anyone wants to see on my Player Character:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.InputSystem;
 
 public class AnimationAndMovementController : MonoBehaviour
 {
 
     PlayerInput playerInput;
     CharacterController characterController;
 
 
     Animator animator;
 
     int isWalkingHash;
     int isRunningHash;
 
     Camera _camera;
 
     Vector2 currentMovementInput;
     Vector3 currentMovement;
     Vector3 currentRunMovement;
 
     bool isMovementPressed;
     bool isRunPressed;
 
     float rotationFactorPerFrame = 15.0f;
     float runMultiplier = 3.0f;
 
 
 
     // Start is called before the first frame update
     void Start()
     {
         _camera = Camera.main;
     }
 
     void Awake()
     {
         playerInput = new PlayerInput();
         characterController = GetComponent<CharacterController>();
         animator = GetComponent<Animator>();
 
         isWalkingHash = Animator.StringToHash("isWalking");
         isRunningHash = Animator.StringToHash("isRunning");
 
 
         playerInput.CharacterControls.Move.started += onMovementInput;
         playerInput.CharacterControls.Move.canceled += onMovementInput;
         playerInput.CharacterControls.Move.performed += onMovementInput;
 
         playerInput.CharacterControls.Run.started += onRun;
         playerInput.CharacterControls.Run.canceled += onRun;
 
     }
 
 
     void onRun(InputAction.CallbackContext context)
     {
         isRunPressed = context.ReadValueAsButton();
     }
 
 
     void onMovementInput(InputAction.CallbackContext context)
     {
 
         currentMovementInput = context.ReadValue<Vector2>();
         currentMovement.x = currentMovementInput.x;
         currentMovement.z = currentMovementInput.y;
 
         currentRunMovement.x = currentMovementInput.x * runMultiplier;
         currentRunMovement.z = currentMovementInput.y * runMultiplier;
 
         isMovementPressed = currentMovementInput.x != 0 || currentMovementInput.y != 0;
 
     }
 
 
 
     void handleAnimation()
     {
         bool isWalking = animator.GetBool(isWalkingHash);
         bool isRunning = animator.GetBool(isRunningHash);
 
         if (isMovementPressed && !isWalking)
         {
             animator.SetBool(isWalkingHash, true);
         }
         else if (!isMovementPressed && isWalking)
         {
             animator.SetBool(isWalkingHash, false);
         }
 
         if ((isMovementPressed && isRunPressed) && !isRunning)
         {
             animator.SetBool(isRunningHash, true);
         }
         else if ((!isMovementPressed && !isRunPressed) && isRunning)
         {
             animator.SetBool(isRunningHash, false);
         }
         else if ((isMovementPressed && !isRunPressed) && isRunning)
         {
             animator.SetBool(isRunningHash, false);
         }
 
     }
 
 
     void handleGravity()
     {
         if (characterController.isGrounded)
         {
             float groundedGravity = -0.05f;
             currentMovement.y = groundedGravity;
             currentRunMovement.y = groundedGravity;
         }
         else
         {
             float gravity = -9.8f;
             currentMovement.y = gravity;
             currentRunMovement.y = gravity;
         }
     }
 
     void handle_isRunPressed()
     {
         if (isRunPressed)
         {
             characterController.Move(currentRunMovement * Time.deltaTime);
         }
         else
         {
             characterController.Move(currentMovement * Time.deltaTime);
         }
     }
 
     void handleRotation()
     {
         // We're getting a Vector2, whereas we will need a Vector3
         // Get a z value based on camera, and include it in a Vector3
         Vector2 mousePosition = playerInput.CharacterControls.MousePosition.ReadValue<Vector2>();
 
         var mousePositionZ = _camera.farClipPlane * .5f;
 
         Vector3 mouseViewportPosition = _camera.ViewportToWorldPoint(new Vector3(mousePosition.x, mousePosition.y, _camera.transform.position.y));
 
 
         Debug.Log("MousePos: " + mouseViewportPosition);
 
         Vector3 positionToLookAt;
         positionToLookAt.x = mouseViewportPosition.x;
         positionToLookAt.y = 0.0f;
         //positionToLookAt.z = currentMovement.z;
         positionToLookAt.z = mouseViewportPosition.z;
 
 
         
 
 
         Quaternion currentRotation = transform.rotation;
         
         Quaternion targetRotation = Quaternion.LookRotation(positionToLookAt - transform.position);
         transform.rotation = Quaternion.Slerp(currentRotation, targetRotation, rotationFactorPerFrame * Time.deltaTime);
         
     }
 
 
     float AngleBetweenTwoPoints(Vector3 a, Vector3 b)
     {
         return Mathf.Atan2(b.y - a.y, b.x - a.x) * Mathf.Rad2Deg;
     }
 
 
 
     // Update is called once per frame
     void Update()
     {
         handleRotation();
         handleAnimation();
         handleGravity();
 
         handle_isRunPressed();
     }
 
 
     void OnEnable()
     {
         playerInput.CharacterControls.Enable();
     }
 
     void OnDisable()
     {
         playerInput.CharacterControls.Disable();
     }
 
 
 }