Question Player script disables the bounciness of my character?

Hi! I'm a new programmer and unity user and I am trying to make a quick game where you play a bouncing ninja fighting of incoming enemies in a simple 2D scene.

Problem:

I have attached a bouncy 2D physics material to my Rigidbody2D on my player character and when I don't have any script attached it works fine. But as soon as I enable the player script which is following:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class PlayerController : MonoBehaviour
6. {
7.     Rigidbody2D rb2d;
8.  
9.     public float speed = 3.0f;
10.     float horizontal;
11.     float vertical;
12.  
13.     public float jumpForce = 2000f;
14.  
15.     void Start()
16.     {
17.         rb2d = GetComponent<Rigidbody2D>();
18.     }
19.  
20.     void Update()
21.     {
22.         horizontal = Input.GetAxis("Horizontal");
23.         vertical = Input.GetAxis("Vertical");
24.  
25.         if (Input.GetKeyDown(KeyCode.Space))
26.         {
27.             Jump();
28.         }
29.  
30.     }
31.  
32.     void FixedUpdate()
33.     {
34.         Vector2 position = rb2d.position;
35.         position.x += speed * horizontal * Time.deltaTime;
36.         position.y += speed * vertical * Time.deltaTime;
37.  
38.         rb2d.MovePosition(position);
39.  
40.     }
41.  
42.     void Jump()
43.     {
44.             GetComponent<Rigidbody2D>().AddForce(Vector2.up * jumpForce);
45.      
46.     }
47. }

My character goes from bouncing smoothly in an even pace to slowly falling down and then staying put to the ground like this when I enable the above script:

 

Correct me if I'm wrong but I don't think you need the Vector2 "position" to calculate your movement on the y-axis,
since you have the jump function. So maybe commenting part out could help.

Code (CSharp):

1. //position.y += speed * vertical * Time.deltaTime;