You're not modeling all elements correctly tho.
Take your water-jug - if the top container is sealed, water will not flow - when unsealed, air is allowed to take the place of the water that flows out. So Air completes the circuit.
Take the sparking - with lightning, the air molecules turn into a plasma-like state, creating a path for the high voltage current to flow.
With a doorknob, the metal in the doorknob gets charged up while you discharge, with the air similarly breaking down as in the lightning example and creating the electrical path.
Simple batteries are much lower voltage tho, so wires are needed from plus to minus, and from minus to plus to close the circuit. It's not until you get into thousands of volts does air breakdown and become a conductor.