Arrays with multiple data types C#

So I've heard this trick is pretty great at just handling data storage. And I wanna learn how to use it, but a few things I'm fuzzy on.

I've read this answer, http://answers.unity3d.com/questions/698312/store-multiple-types-of-data-in-an-array.html but unfortunately I'm still learning C# and there are some things I'm fuzzy on. If I create a class;

 using UnityEngine;
 using System.Collections;
 using UnityEngine.UI;
 
 public class ButtonData : MonoBehaviour
 {
     public GameObject    buttonGameObject;
     public Image          buttonImage;
     public Button         button;
     public float         coolDown;
     public int            value;
 }
 

And then I call that class to create an array within another class;

     public ButtonData[]            allButtonData;    

How come if I remove : MonoBehavior from the ButtonData class, the array of buttonData [] disappears in the inspector?

And where do I fill in the values of each entry? It can't be done within the inspector as that only seems to be looking for objects containing that class?

I guess I was sort of expecting a means to house data and then enter that data in the inspector like you can with any other single data type array.

So if anyone knows of a great tutorial page or documentation as to how and coders use this method, I'd love to read it.