Benjamin Franklin discovered it [electricity] . . .
Nope. Though that is a commonly held misconception. He experimented with it as others had done and popularized it in Europe and America. Electricity has been experimented with for at least 2,000 years. The first person to conduct serious experiments and record the results was William Gilbert in the court of Elizabeth I, around 150 years before Franklin. Franklin did invent the lightning rod, which is considered the first practical device involving electricity, though not technically an electrical device.
History of Electricity
I would say the American system of government changed not only this country, but the world in profound ways. I don't know if that qualifies as an invention in the sense you're asking, and it does draw on other models - the ancient Greeks, the Romans, and the Iroquois nation. But I think as much as anything it has changed the world in the past 200 years or so.
