Community can not be defined? You are reading entirely too much Ayn Rand and maggie Thatcher. There nothing “abstract” about it. The Human Species has always been a SOCIAL grouping. It is how they were able to survive against species much better equipped to survive then they are.
Human babies are not fully developed when they are born . In order to be born at the same level of development of other species, they would have to be in the womb for some 21 months. A number of studies have shown that the development outside the womb is due in great part to the social and communal makeup of our species and this exposure as infants to other members of a given tribe helped impress SOCIAL awareness on the infant as a member of that community. The Community or tribe in turn protected that baby through its infancy.
Watch a Calf being born. Within hours of its birth it can get up and walk. A human baby is not only born naked (relying on ANOTHER to provide warmth) but can not walk for the first year after birth.
The protection of said infant through virtually ALL of human history was a collective effort rather then one that relied soley on the direct parents. The Human Species ability to survive was because they acted as a collective and tribal group rather then a collection of isolated individuals just trying to pass on their genes. Primates that are isolated from the community in the wild exhibit anti-social behaviour within the same and will suffer from ill health and lowered life expectancies.
In the United States itself studies have shown that much of the depression exhibited in its population and consequent ill health is due to Social isolation and the breakdown of community. The rise in mental illness is a direct consequence of this, and with it higher use of anti-depressants and other drugs.