Can't Stop Rotation along the Z Axis

I am attempting to create a first person camera system, based on a video tutorial I've seen online. However, the issue is that I cannot stop the player character being able to rotate along the Z axis. I have attempted a few different solutions but I have found myself unable to fix the problem. The code appears to ignore the Rigidbody restrictions regarding rotating along the Z axis. I'm guessing its an issue with how the code performs the translation function. Can anyone suggest a way I could fix this? For reference I have added in the code itself as well as a screenshot of the Inspector panel for the player character.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class camMouseCont : MonoBehaviour
 {
     Vector2 mouseLook;
     Vector2 smoothV;
     public float sensitivity = 5.0f;
     public float ySense = 0.0f;
     public float smoothing = 2.0f;
 
     GameObject player;
 
     // Use this for initialization
     void Start()
     {
         //Finds the Game Object that the script is connected to allowing 
         player = this.transform.gameObject;
         Debug.Log(player);
     }
 
     // Update is called once per frame
     void Update()
     {
         var md = new Vector2(Input.GetAxisRaw("Mouse X"), Input.GetAxisRaw("Mouse Y"));
 
         md = Vector2.Scale(md, new Vector2(sensitivity * smoothing, ySense * smoothing));
         smoothV.x = Mathf.Lerp(smoothV.x, md.x, 1f / smoothing);
         smoothV.y = Mathf.Lerp(smoothV.y, md.y, 1f / smoothing);
         mouseLook += smoothV;
 
         if (mouseLook.y < -30)
         {
             mouseLook.y = -30;
         }
 
         if (mouseLook.y > 30)
         {
             mouseLook.y = 30;
         }
 
         transform.localRotation = Quaternion.AngleAxis(-mouseLook.y, Vector3.right);
         player.transform.localRotation = Quaternion.AngleAxis(-mouseLook.x, player.transform.up);
         player.transform.localRotation = Quaternion.AngleAxis(0, player.transform.forward);
     }
 }