The false appearance of conspiracy can easily arise when you have numerous people with roughly aligned ideologies and incentives independently responding to similar stimuli in whatever way they personally think is the most prudent. That's probably what's going on here.

This idea was explained by Chomsky in Manufacturing Consent.

By those criteria human society would appear to be a conspiracy.

No, a conspiracy has a very specific definition that has gotten lost in all the noise:

noun (plural conspiracies)

a secret plan by a group to do something unlawful or harmful: she served five years in prison for taking part in a conspiracy to sell stolen art works.

The key is that it's a secret plan. People have to have gotten together to meet, in secret, and agree on a plan. This is why true grand conspiracies are so rare: it's hard to get a lot of people together in one room, get them all to agree on a plan, and get them all to keep it a secret. The more people involved, the more likely there will be a leaker.

Criminal conspiracies are quite common though. Of course, those can involve as few as 2 people making a plan to commit a crime together.

People who live far outside of the mainstream do often come to believe that mainstream society is all one grand conspiracy. That perception is an illusion, created by the mechanism I described.