Lots of people been eating round flat bread with toppings around the Mediterranean for a very long time now.
One of the theories of the modern Pizza origin is that it was just a Pizza like any other (or Pitta...) until a certain restaurant in Naples invented the version with tomato sauce (the Marinara Pizza). And modern Pizza are just variations of the dish of that restaurant.
By the way, that restaurant still exists, or so people claim. https://en.wikipedia.org/wiki/Antica_Pizzeria_Port'Alba