The Greeks jerked human history in a completely unexpected direction. They invented rationalism, a form of rigorous sequential thinking that ultimately led to science and technology. The idea of rationalism is so alien to the human mind that it took 2,000 years for people to fully implement rationalism. When they did, it changed the world more profoundly than anything in history.
The Greek achievement was neither predictable nor likely. It came about due to a series of accidents and oddities that could not have obtained anywhere else. All the pieces of a strange new puzzle came together to produce Greece.