The Invention of Discovery, if that makes sense? Basically whoever it was who made the first discovery about the natural world, whether that discovery was mating or fire or a very rudimentary understanding of physics. Discovering discovery is what led to man creating societies, buildings, the lightbulb, the washing machine, the internet, spaceships. All of science, mathematics, and society hinged on that man hundreds and thousands of years ago who invented curiosity and sought to discover something about the world, whatever that discovery was.

That or alternating current. The switch from gaslamps to electric lights allowed other inventors to stay up later creating plans. It also allowed them to communicate faster and easier across vast distances. It also changed the way the world operates, allowing workers to work later into the night instead of working at the crack of dawn. Alternating current allowed electricity to reach across vast distances of land a lot more efficiently than a direct current, which would require a transformer or power station every couple of blocks in a large city.