Why is overriding necessary for the clone() method in the class if we are calling the clone() on the instance of the class in some other class?

Question

class Cat {

    int j;

    Cat(int j) {
        this.j = j;
    }
}

class Dog implements Cloneable {

    int i;
    Cat c;

    Dog(Cat c, int i) {
        this.c = c;
        this.i = i;
    }

    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

class ShallowCloneDemo {

    public static void main(String[] args) throws Exception {
        Cat c = new Cat(20);
        Dog d1 = new Dog(c, 10);
        System.out.println(d1.i + " ... " + d1.c.j);

        Dog d2 = (Dog) ((Object) d1).clone();
        d2.i = 888;
        d2.c.j = 999;
        System.out.println(d1.i + " ... " + d2.c.j);
    }
}

In the above program I am calling the clone() method on d1 object inside the ShallowCloneDemo class, so why can't I call the clone() of the Object class(superclass) without overriding clone() in the Dog class?

When I tried calling the clone() from the same Dog class rather than calling it from other class then it worked without any error:

class Cat {

    int j;

    Cat(int j) {
        this.j = j;
    }
}

class Dog implements Cloneable {

    int i;
    Cat c;

    Dog(Cat c, int i) {
        this.c = c;
        this.i = i;
    }

    public static void main(String[] args) throws Exception {
        Cat c = new Cat(20);
        Dog d1 = new Dog(c, 10);
        System.out.println(d1.i + " ... " + d1.c.j);

        Dog d2 = (Dog) d1.clone();
        d2.i = 888;
        d2.c.j = 999;
        System.out.println(d1.i + " ... " + d2.c.j);
    }
}

However, when I tried removing the override of clone() inside the Dog class and called the clone() method from the ShallowCloneDemo class on the d1 object:

class Cat {

    int j;

    Cat(int j) {
        this.j = j;
    }
}

class Dog implements Cloneable {

    int i;
    Cat c;

    Dog(Cat c, int i) {
        this.c = c;
        this.i = i;
    }
}

class ShallowCloneDemo {
    public static void main(String[] args) throws Exception {
        Cat c = new Cat(20);
        Dog d1 = new Dog(c, 10);
        System.out.println(d1.i + " ... " + d1.c.j);

        Dog d2 = (Dog) ((Object) d1).clone();
        d2.i = 888;
        d2.c.j = 999;
        System.out.println(d1.i + " ... " + d2.c.j);
    }
}

then I was having the following compilation issue:

error: clone() has protected access in Object Dog d2 = (Dog)d1.clone();

I am confused as per the definition of the protected access modifier I should be able to call the protected method from anywhere of the same package. I am writing this program on Notepad of Windows and not providing any declaration for the package and also I am saving all these programs in the same folder.