The main type of Linked List Queue that extends the base Node <T> in Java + Requesting Laymans Terms

Firstly, yes, this is for the assignment at school, but I'm not looking for someone to rewrite or change my code. My question is:

I am invited to write a class that creates a queue that extends Node (the latter, as shown below)

public class Node<T>{
  protected      T  data;
  protected Node<T> next; 
}

I wrote (most likely, very rude) a method for this and a basic test program that stores integer types in a queue (hopefully). I don’t know all the professional jargon, I read the “generics” documentation, but I might have missed the key point, I read how the linked list works (their examples are more in the Node class, something I’m not allowed to edit this task), and also circular arrays, etc. when I run my code, I get an error that I did not expect from the types. I will post my corresponding code, can someone please explain what I did to get this (rather ... where would I not use in my code?)

public class Queue<T> extends Node<T> {

    public Node base;
    public Node end;

    public void enqueue(T item) {

        Node newItem = new Node();
        newItem.data = item;
        newItem.next = null;

        if (isEmpty()) { //Sets to item count of 1
            this.base = newItem; //Base becomes the new item
            this.base.next = this.end; //Base Points Next as End
            this.end.next = this.base; //End points to the one before it (base)
        } 
        else { //Sets to item count above 1.
            this.end.next.next = newItem; //The Last Item Now Points Next as the New Item (End is never counted as an item)
            this.end.next = newItem; //End now points to the next final item.
        }

    }

    public T dequeue() {

        if (isEmpty()) {
            return (null);
        }

        else {
            T item = this.base.data;

            if (this.base.next == this.end) {
                this.base = null;
                this.end = null;
            }

            else {
                this.base = this.base.next;
            }

            return (item);
        }

    }

    public int size() {

        int count = 0;

        for (Node node = base; node != null; node = node.next) {
            count++;
        }
        return count;

    }

    public boolean isEmpty() {

        return (base == null);

    }

    public Queue() {

        this.base = null;
        this.end = null;

    }
 }

Code TestQueue.java:

public class TestQueue {

    public static void main(String args[]) {

        QueueStuff<Integer> firstQueue = new QueueStuff<>();

        firstQueue.enqueue (66);
        firstQueue.enqueue (6);
        firstQueue.enqueue (666);
        firstQueue.enqueue (0);
        firstQueue.enqueue (6666);

        //firstQueue.printQueue();
    }

}

And the error is this:

incompatible types. 
   T item = this.base.data;
                     ^
   required: T
   found:    Object
   where T is a Type variable: T extends Object declared in class Queue