Why does my character fall slowly even though rigid.drag = 0?

https://www.youtube.com/watch?v=F-bwle2BPiA&feature=youtu.be

The video above says all.

Here is the following code I used if you cannot see the video in HD yet:

 public class CameraManager : MonoBehaviour 
 {
     public float followSpeed;
     public Transform target;
     public Transform cam;
 
     public static CameraManager singleton;
 
     void Awake()
     {
         singleton = this;
     }
 
     public void Init(Transform t)
     {
         target = t;
         cam = Camera.main.transform;
     }
 
     public void FixedTick(float d)
     {
         FollowTarget (d);
     }

     void FollowTarget(float d)
     {
         Vector3 targetPosition = Vector3.Lerp (transform.position, target.position, d * followSpeed);
         transform.position = targetPosition;
     }
 
 }

 public class InputManager : MonoBehaviour 
 {
     public float horizontal;
 
     CameraManager cam;
     StatesManager states;
 
     [HideInInspector]
     public float delta;
 
     void Start () 
     {
         cam = CameraManager.singleton;
         states = GetComponent<StatesManager> ();
 
         states.Init();
         cam.Init(this.transform);
     }
 
     void FixedUpdate()
     {
         delta = Time.fixedDeltaTime;
         GetInput ();
         UpdateStates ();
         states.FixedTick (delta);
         cam.FixedTick (delta);
     }
 
     void Update () 
     {
         delta = Time.deltaTime;
 
     }
 
     void GetInput()
     {
         horizontal = Input.GetAxis ("Horizontal");
     }
 
     void UpdateStates()
     {
         states.horizontal = horizontal;
         states.moveDir = new Vector3 (horizontal, 0, 0);
         states.moveAmount = horizontal;
         states.moveAmount = Mathf.Abs (states.moveAmount);
     }
 }

 public class StatesManager : MonoBehaviour 
 {
     [Header ("Initialization")]
     public GameObject activeModel;
 
     [Header ("Inputs")]
     public float horizontal;
     public float moveAmount;
     public Vector3 moveDir;
 
     [Header ("Stats")]
     public float moveSpeed;
     public float dashSpeed;
     public float rotateSpeed;
 
     [Header ("States")]
     public bool onGround;
     public bool inAction;
     public bool canMove;
     public bool dashing;
     public bool jumping;
 
     [HideInInspector]
     public Animator anim;
     [HideInInspector]
     public Rigidbody rigid;
 
 
     public void Init () 
     {
         SetUpAnim ();
         SetUpRigid ();
     }
 
     public void FixedTick(float d)
     {
         HandleMovementAndRotations (d);
         HandleAnims (d);
     }
 
 
     public void Tick (float d) 
     {
         
     }
 
     void HandleAnims(float d)
     {
         anim.SetFloat ("vertical", moveAmount, 0.1f, d);
     }
 
     void HandleMovementAndRotations(float d)
     {
         rigid.drag = (moveAmount > 0 || onGround == false) ? 0 : 4;
         
         rigid.velocity = moveDir * (moveSpeed * moveAmount);
 
         if (moveDir == Vector3.zero)
             moveDir = Vector3.forward;
         Quaternion tr = Quaternion.LookRotation (moveDir);
         Quaternion targetRotation = Quaternion.Slerp (transform.rotation, tr, d * moveAmount * rotateSpeed);
         transform.rotation = targetRotation;
 
     }
 
     void SetUpAnim()
     {
         if (activeModel == null) {
             anim = GetComponentInChildren<Animator> ();
             if (anim == null) 
             {
                 Debug.Log ("No model found.");
             } 
             else 
             {
                 activeModel = anim.gameObject;
             }
         }
 
         if (anim == null) 
             anim = activeModel.GetComponent<Animator> ();
 
         anim.applyRootMotion = false;
             
     }
 
     void SetUpRigid()
     {
         rigid = GetComponent<Rigidbody> ();
         rigid.angularDrag = 999;
         rigid.drag = 4;
         rigid.constraints = RigidbodyConstraints.FreezeRotationX | RigidbodyConstraints.FreezeRotationZ;
     }
 }
 

And yes, the gravity is at it's default -9.81 setting, but I'd like to avoid messing with that option since it might complicate things down the road.

pls help me. ive tried for a week. im desperate. thank you.