The cooling system recirculates, giving a better analogy to an electrical circuit. Fluid in the cooling system starts at the water pump and flows through the engine and the radiator before returning to the pump to start all over again. Water from the garden hose does not return directly to the faucet. They definitely do not measure the same thing. These are different concepts.
Volts produce amps in a circuit.
Circuit 5 is the only one that has current flowing through the lamp. In circuit 3, both ends of the lamp filament are at the same potential, so no current flows. In circuit 4, only one end of the filament is connected to one terminal of the battery. The other terminal is connected to the glass bulb, which does not readily conduct electricity. Everything may not be okay, if the alternator was failing to charge the battery.