Should I scrap my 2D Character Controller because of how I shortsightedly started to build it?

Hello! I've been trying to create the framework for a game for the past couple of days and came across one of the first major hurdles... slopes. I've been stumped on how to tackle them for a few hours now, and I debating starting all over in my script but this time dealing with raycasts instead of just creating new vector2's and changing the physics. Is that a good idea? Can someone help me figure out the logical next step to tackling slopes in my script?

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class PlayerController : MonoBehaviour
6. {
7.     public float moveSpeed = 400f;
8.     public float jumpVelocity;
9.     public float lowJumpMult = 2f;
10.     public float fallMult = 2.5f;
11.     public float airResist = 0f;
12.  
13.     Rigidbody2D rb;
14.  
15.     private bool isGrounded;
16.     // Start is called before the first frame update
17.     void Start()
18.     {
19.         rb = GetComponent<Rigidbody2D>();
20.         isGrounded = false; //to check if the player is on the ground so that they can't jump twice
21.     }
22.  
23.     private void OnTriggerEnter2D(Collider2D collider)
24.     {
25.         if (collider.gameObject.tag == ("Terrain"))
26.         {
27.             isGrounded = true;
28.         }
29.     }
30.  
31.     // Update is called once per frame
32.     void Update()
33.     {
34.         if (Input.GetKey(KeyCode.RightArrow)) //moving right
35.         {
36.             if (isGrounded)
37.             {
38.                 rb.velocity = new Vector2 (moveSpeed * Time.deltaTime, rb.velocity.y);
39.             }
40.             else
41.             {
42.                 rb.velocity =  new Vector2 (moveSpeed * Time.deltaTime * airResist, rb.velocity.y);
43.             }
44.         }
45.  
46.         if (Input.GetKey(KeyCode.LeftArrow)) //moving left
47.         {
48.             if (isGrounded)
49.             {
50.                 rb.velocity = new Vector2(moveSpeed * Time.deltaTime * -1, rb.velocity.y);
51.             }
52.             else
53.             {
54.                 rb.velocity = new Vector2(moveSpeed * Time.deltaTime * airResist * -1, rb.velocity.y);
55.             }
56.         }
57.  
58.  
59.         if (rb.velocity.x >= 0 && !Input.GetKey(KeyCode.RightArrow)) //stop moving on the x axis when the right key is released
60.         {
61.             rb.velocity = new Vector2(0 * Time.deltaTime, rb.velocity.y);
62.         }
63.  
64.         if (rb.velocity.x <= 0 && !Input.GetKey(KeyCode.LeftArrow)) //stop moving on the x axis when the left key is released
65.         {
66.             rb.velocity = new Vector2(0 * Time.deltaTime, rb.velocity.y);
67.         }
68.  
69.         if (Input.GetButtonDown("Jump") && isGrounded == true) //jumping
70.         {
71.             rb.velocity = (Vector2.up * jumpVelocity);
72.             isGrounded = false; //making sure that when ur in the air you cannot jump a second time
73.         }
74.  
75.         if (rb.velocity.y < 0)
76.         {
77.             rb.velocity += Vector2.up * Physics2D.gravity.y * (fallMult - 1) * Time.deltaTime; //falling faster for weighty physics
78.         }
79.         else if (rb.velocity.y > 0 && !Input.GetButton("Jump"))
80.         {
81.             rb.velocity += Vector2.up * Physics2D.gravity.y * (lowJumpMult - 1) * Time.deltaTime; //dynamic jump (when key is released gravity is increased)
82.         }
83.  
84.     }
85.  
86. }
87.  

This is what my code looks like and I don't know if I went about it the right way or not. Thanks in advance to anyone brave enough to help me!