sorry, your example is still not complete nor working. I don't know what is inside App class, and what class godzilla, dino, etc belongs to.
check this example, it does what you want to. maybe you can use it in your code.
#include <SFML/Graphics.hpp>
int main(){
sf::RenderWindow window(sf::VideoMode(800, 600), "SFML");
sf::CircleShape circle1(50.f);
sf::CircleShape circle2(50.f);
circle1.setFillColor(sf::Color::Blue);
circle2.setFillColor(sf::Color::Red);
circle1.setPosition(100, 100);
circle2.setPosition(400, 400);
while (window.isOpen()){
sf::Event event;
while (window.pollEvent(event)){
if (event.type == sf::Event::Closed){
window.close();
}
}
//Moving Circle 1
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Left)){
circle1.move(-1.f, 0.f);
}
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Right)){
circle1.move(1.f, 0.f);
}
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Up)){
circle1.move(0.f, -1.f);
}
if (sf::Keyboard::isKeyPressed(sf::Keyboard::Down)){
circle1.move(0.f, +1.f);
}
//Moving Circle 2
if (sf::Keyboard::isKeyPressed(sf::Keyboard::A)){
circle2.move(-1.f, 0.f);
}
if (sf::Keyboard::isKeyPressed(sf::Keyboard::D)){
circle2.move(1.f, 0.f);
}
if (sf::Keyboard::isKeyPressed(sf::Keyboard::W)){
circle2.move(0.f, -1.f);
}
if (sf::Keyboard::isKeyPressed(sf::Keyboard::S)){
circle2.move(0.f, +1.f);
}
window.clear(sf::Color::White);
window.draw(circle1);
window.draw(circle2);
window.display();
sf::sleep(sf::milliseconds(10));
}
}