2d movement unity

//player must have a rigidbody2D and a box colider
public float moveSpeed = 5f;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        Jump();
        Vector3 movement = new Vector3(Input.GetAxis("Horizontal"), 0f, 0f);
        transform.position += movement * Time.deltaTime * moveSpeed;
    }

    void Jump()
    {
        if (Input.GetButtonDown("Jump"))
        {
            gameObject.GetComponent<Rigidbody2D>().AddForce(new Vector2(0f, 5f), ForceMode2D.Impulse);
        }
    }public class PlayerMovement : MonoBehaviour
{
    public float moveSpeed;
    public float jumpHeight;

    void Start()
    {
    
    }

    void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, jumpHeight);
        }

        if (Input.GetKey(KeyCode.D))
        {
            GetComponent<Rigidbody2D>().velocity = new Vector2(moveSpeed, 0);
        }

        if (Input.GetKey(KeyCode.A))
        {
            GetComponent<Rigidbody2D>().velocity = new Vector2(-moveSpeed, 0);
        }
    }
}