Why did people long ago form communities

Because they would have no trade or skill in a new land to find food and try to survive. A group of people are more likely to survive then just one group of people. Plus hundreds of people were normally sent on a ship to the new place to form a colony or they were having problems with the old country and needed to leave to be them. There are many more too. Let me know if you need any

There could be many different reasons.

farming collectives

security needs