Jumping doesn't work when holding the ball

I'm making a first person basketball game. I think my two scripts (throw object and jump) are colliding with each other.

The problem is that I can't jump when I'm holding the ball. Or when I'm in the air while jumping and grab the ball, I freeze in whatever height I grabbed the ball in, but I can still move.

Could someone tell me whats wrong and provide some answers? Thank you in advance. <<<<<<<<<<< Edit: I fixed the issue of not being able to jump by changing the ground from being a terrain to a flattened cube, but I still freeze in the air when I grab the ball.>>>>>>>>> <<<<<<<<<<< Edit: Well, the jump works sometimes, sometimes not. I can't figure out what't the problem.

Here's the throw object script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class ThrowObject : MonoBehaviour
 {
     public Transform player;
     public Transform theDest;
     public float throwForce = 10;
     bool hasPlayer = false;
     bool beingCarried = false;
     private bool touched = false;
 
 
 
     void Update()
     {
         float dist = Vector3.Distance(gameObject.transform.position, player.position);
         if (dist <= 2.5f)
         {
             hasPlayer = true;
         }
         else
         {
             hasPlayer = false;
         }
         if (hasPlayer && Input.GetButtonDown("Use"))
         {
             GetComponent<Rigidbody>().isKinematic = true;
             transform.parent = theDest;
             beingCarried = true;
         }
 
 
 
         if (beingCarried)
         {
             if (touched)
             {
                 GetComponent<Rigidbody>().isKinematic = false;
                 transform.parent = null;
                 beingCarried = false;
                 touched = false;
             }
             if (Input.GetMouseButtonDown(1))
             {
                 GetComponent<Rigidbody>().isKinematic = false;
                 transform.parent = null;
                 beingCarried = false;
                 GetComponent<Rigidbody>().AddForce(theDest.forward * throwForce);
                 
             }
             else if (Input.GetMouseButtonDown(0))
             {
                 GetComponent<Rigidbody>().isKinematic = false;
                 transform.parent = null;
                 beingCarried = false;
             }
         }
     }
     void OnTriggerEnter()
     {
         if (beingCarried)
         {
             touched = true;
         }
     }
 
 }

And here's the jump script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using System.Collections;
 
 
 public class Jump : MonoBehaviour
 {
 
     public Vector3 jump;
     public float jumpForce = 2.0f;
 
     public bool isGrounded;
     Rigidbody rb;
     void Start()
     {
         rb = GetComponent<Rigidbody>();
         jump = new Vector3(0.0f, 2.0f, 0.0f);
     }
 
     void OnCollisionStay()
     {
         isGrounded = true;
     }
 
     void Update()
     {
         if (Input.GetKeyDown(KeyCode.Space) && isGrounded)
         {
 
             rb.AddForce(jump * jumpForce, ForceMode.Impulse);
             isGrounded = false;
         }
     }
 }