错误：“无法将类型“System.Collections.Generic.IEnumerable”隐式转换为“System.Collections.Generic.List”

我试图将一个数字列表转换成字符串，然后再转回列表。转换成字符串没有问题，但当我将其转回列表时，出现了错误“无法隐式转换类型'System.Collections.Generic.IEnumerable'。这是我运行的代码。

using System;
using System.Collections.Generic;
using UnityEngine;
using System.Linq;
using System.Globalization;
public class Test : MonoBehaviour
{
    void Start()
    {
        Function();
    }
    void Function()
    {
        List listBuffer = new List();
        System.Random rnd = new System.Random();
        for (int x = 1; x < 100; x++)
        {
            listBuffer.Add(x);
        }
        List listInt = (from item in listBuffer
                               orderby rnd.Next()
                               select item).ToList();
        print(listInt[0]);
        string stringBuffer = String.Join(", ", listInt.Select(n => n.ToString(CultureInfo.InvariantCulture)).ToArray());
        print(stringBuffer);
        List listInt2 = stringBuffer.Split(',').Select(c => Int32.Parse(c, CultureInfo.InvariantCulture)).ToList();
        print(listInt2[0]);
    }
}