Не могу сделать полиморфизм. Не могу до конца понять пример по этому поводу

#include <iostream>
using namespace std;
 
class Animal
{
    protected:
              string animalName;
              float weightAnimal;
    public:
        inline void setAnimal(string, float);
        virtual void showInfo()=0;
        virtual ~Animal() = default;
};
 
class Reptile: public Animal{
    protected:
            string habitat;
    public:
            Reptile();
            Reptile(string,float,string);
            void showInfo();
};
 
class Snake: public Reptile{
    private:
            bool poisonous;
    public:
            Snake();
            Snake(string,float,string,bool);
            void showInfo();
};
 
//class implementation
//class Animal, display function
void Animal::setAnimal(string name, float weight)
{
    animalName=name;
    weightAnimal=weight;
}
 
void Animal::showInfo(){
    cout<<"Name of the Animal : "<<animalName<<endl;
    cout<<"Weight : "<<weightAnimal<<endl;
}
 
//class implementation
//class Reptile, display function
Reptile::Reptile()
{
    animalName="None";
    weightAnimal=0;
    habitat="None";
}
 
Reptile::Reptile(string name, float weight, string habitat)
{
    setAnimal(name,weight);
    habitat=habitat;
}
 
void Reptile::showInfo()
{
    Animal::showInfo();
    cout<<"Habitat: "<<habitat<<endl;
}
 
//class implementation
//class Snake, display function
Snake::Snake()
{
    animalName="None";
    weightAnimal=0;
    habitat="None";
    poisonous=false;
}
 
Snake::Snake(string name, float weight, string habitat,bool poison):Reptile(name,weight,habitat)
{
    poisonous=poison;
}
 
void Snake::showInfo(){
 
    Reptile::showInfo();
    cout<<"Poisonous: ";
    if (poisonous==1)
        cout<<"Yes"<<endl;
    else
        cout<<"No"<<endl;
}
 
//Driver function to test the functionality of the classes
int main(){
 
    Reptile reptile("Lion",123,"Earth");
    Snake snake("Cobra",125,"Water",true);
 
    Animal *animal1=&reptile;
    Animal *animal2=&snake;
 
    animal1->showInfo();
    animal2->showInfo();
 
}

this->habitat=habitat;

Reptile reptile("Лев",123,"Земля");
Snake snake("Кобра",125,"Вода",true);
Reptile r("Свинка",123,"Земля");
Snake s("макака",125,"Земля",true);
 
Animal * tri[4]== {&reptile, &snake, &r, &s};
for(int i=0; i<4; i++)
{
    tri[i]->showInfo();
}

struct A
{
    virtual ~A() = 0;
};
 
struct B : A
{
    ~B(){}
};
 
int main()
{
    A *a = new B;
    delete a;
}

virtual ~Animal(){}