Can we call non static member functions without creating object?

If not, the following code is behaving like we can call non-static member functions without creating objects. Please clarify on this.

Main file:

    #include <iostream>
    #include "singleton.h"

    int main() {
            Singleton* ptr = Singleton::createInstance();
            Singleton* ptr1 = Singleton::createInstance();
            std::cout << "Object ptr: " << ptr;
            ptr->showDetails();
            return 0;
    }

Singleton.h:

    class Singleton {
            Singleton();
            public:
            static Singleton* ptr;
            ~Singleton();
            void showDetails();
            static Singleton* createInstance();
    };

Singleton.cpp

#include <iostream>
#include <cstddef>

#include "singleton.h"

Singleton* Singleton::ptr = nullptr;

Singleton::Singleton() {
        std::cout << "Singleton constructor called." << std::endl;
}

Singleton::~Singleton() {
        std::cout << "Singleton destructor called." << std::endl;
}

Singleton* Singleton::createInstance() {
        std::cout << "Singleton createInstance called." << std::endl;
        return ptr;
}

void Singleton::showDetails() {
        std::cout << "This is the singleton class." << std::endl;
}

OUTPUT: ./app Singleton createInstance called. Singleton createInstance called. Object ptr: 0This is the singleton class.