who invented circuits?

Answer 1

The first circuit was invented by Thomas A. Edison by creating the most basic circuit: Power supply (Power generator) + Resistance (Light bulb). Texas Instruments invented the first chip, which basicly made a circuit programmable.
The modern circuit boards are just a neater way of putting all the electronic components using the smallest pieces available and occupying a very little space.

Answer 2

No one. They are just a completed path through which current (electrons) can flow. The flow of electrons in a lightening strike is through a completed path and lightening was striking long before we were here.