How to limit a Unity2D character?

Question

2D

In general, I wrote a small toy, but it is so-so.

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Run : MonoBehaviour 
{
  public float speed = 0.01f;

  private void Update()
  {
    transform.position += new Vector3(0, speed, 0) * Input.GetAxis("Vertical");
  }
}

All code.
It is necessary to somehow make a constraint for the character using RigidBody2D and the colliders get twitchy, how could this be fixed?