How to move a list of obstacles?

Unity Engine
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1

I want each obstacle inside my obstacle list to move backwards in y direction but the obstacles are just spawning and not moving.

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

public class Enemyscript : MonoBehaviour
{
    // Start is called before the first frame update
    public GameObject[] obstacles;
    float smallspawntime;
    private float speed = -20f;
    public void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        if (Time.time > smallspawntime)
        {   
            int obsIndex = Random.Range(0, obstacles.Length);
            Vector3 Obstaclepos = new Vector3(Random.Range(-4.08f, 4.4f), -1.345564f, 60);
            Instantiate(obstacles[obsIndex], Obstaclepos, Quaternion.Euler(0, 180, 0));
            smallspawntime = Time.time + Random.Range(0.2f, 1.3f);
        }
        Vector3 obstaclemovement = new Vector3(0, 0, speed * Time.deltaTime);
        foreach (GameObject obstacle in obstacles) 
        {
            obstacle.transform.position += obstaclemovement;
        }

    }
}

Is there anyway I can do this without a separate script for each obstacles?

2 
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Enemyscript : MonoBehaviour
{
    public GameObject[] obstacles;
    float smallspawntime;
    private float speed = -20f;
    List<GameObject> spawned=new List<GameObject>();

    void Update()
    {
        if (Time.time > smallspawntime)
        {   
            int obsIndex = Random.Range(0, obstacles.Length);
            Vector3 Obstaclepos = new Vector3(Random.Range(-4.08f, 4.4f), -1.345564f, 60);
            GameObject obs=Instantiate(obstacles[obsIndex], Obstaclepos, Quaternion.Euler(0, 180, 0));
            spawned.Add(obs);
            smallspawntime = Time.time + Random.Range(0.2f, 1.3f);
        }
        Vector3 obstaclemovement = new Vector3(0, 0, speed * Time.deltaTime);
        foreach (GameObject obstacle in spawned) 
        {
            obstacle.transform.position += obstaclemovement;
        }
    }
}