I'm making a 2d platformer. I got the camera to follow me, but when I jump up the whole camera goes up. How do I make the camera stay focused in on one view instead of going up and down?

 using UnityEngine;
 
 namespace UnitySampleAssets._2D
 {
 
     public class Camera2DFollow : MonoBehaviour
     {
 
         public Transform target;
         public float damping = 1;
         public float lookAheadFactor = 3;
         public float lookAheadReturnSpeed = 0.5f;
         public float lookAheadMoveThreshold = 0.1f;
 
         private float offsetZ;
         private Vector3 lastTargetPosition;
         private Vector3 currentVelocity;
         private Vector3 lookAheadPos;
 
         // Use this for initialization
         private void Start()
         {
             lastTargetPosition = target.position;
             offsetZ = (transform.position - target.position).z;
             transform.parent = null;
         }
 
         // Update is called once per frame
         private void Update()
         {
 
             // only update lookahead pos if accelerating or changed direction
             float xMoveDelta = (target.position - lastTargetPosition).x;
 
             bool updateLookAheadTarget = Mathf.Abs(xMoveDelta) > lookAheadMoveThreshold;
 
             if (updateLookAheadTarget)
             {
                 lookAheadPos = lookAheadFactor*Vector3.right*Mathf.Sign(xMoveDelta);
             }
             else
             {
                 lookAheadPos = Vector3.MoveTowards(lookAheadPos, Vector3.zero, Time.deltaTime*lookAheadReturnSpeed);
             }
 
             Vector3 aheadTargetPos = target.position + lookAheadPos + Vector3.forward*offsetZ;
             Vector3 newPos = Vector3.SmoothDamp(transform.position, aheadTargetPos, ref currentVelocity, damping);
 
             transform.position = newPos;
 
             lastTargetPosition = target.position;
         }
     }
 }