Why cant I jump in an pure ai generated code?

This is code 100% ai generated and I now about coding can somebody tell me the mistake?

sing UnityEngine;

public class PlayerController : MonoBehaviour
    public float moveSpeed = 5f;
    public float jumpForce = 10f;
    public Transform groundCheck;
    public LayerMask groundLayer;

    private Rigidbody2D rb;
    private bool isGrounded;
    private float groundCheckRadius = 0.1f;

    private void Start() => rb = GetComponent<Rigidbody2D>();

    private void Update()
        isGrounded = Physics2D.OverlapCircle(groundCheck.position, groundCheckRadius, groundLayer);

        float horizontalInput = Input.GetAxis("Horizontal");
        // Use the space key for jumping
        if (Input.GetKeyDown(KeyCode.Space) && isGrounded)
            rb.velocity = new Vector2(rb.velocity.x, jumpForce);

        rb.velocity = new Vector2(horizontalInput * moveSpeed, rb.velocity.y);

Thats my only code


a picture of the code: