...and resources harvesting and processing would be nutrition and metabolism, currency the blood circulating, communication the nervous system, then... wouldn't government be the brain?
the blood circulating == trucks, cars, buses, trains, ships, airplanes
really, what would the currency be?
Organisms use multiple "currencies" for different purposes. Fat for long term high density storage, glucose for everyday activities, and ketone bodies in times of starvation.
I think it is wrong to separate the "brain" and the nervous system. The brain is a location of highly dense nervous system activity that filters unimportant information and tries to predict the results of current/future actions on future results based on past experience. I'm not sure what the analogous thing in a society would be, not the government.
The government is more like the immune system (as blackbison says), which has various tools to detect and deal with internal and external threats to the stability of the system.