Q:

Where did the primordial reputation come from?

In the beginning there was Stack Overflow. Then Jeff Atwood created reputation. And he looked and saw it was good. 
But there was one problem. In order to get reputation, you need upvotes, and nobody had enough reputation to upvote. Can you show me where the very first reputation points came from?

A:

There are some competing theories about how the Primordial Reputation came into being.
Intelligent Design
Under this theory, the First Users did not need reputation to have upvoting rights. The system was intelligently designed to avoid the paradox you point out. Having a minimum reputation for voting was only added later via an evolutionary process.
Panspermia
The Primordial Reputation fell upon some of the First Users from a distant alien world, perhaps where reputation was not needed to vote. It bestowed them with the reputation needed to upvote, thus allowing them to grant those rights to others.
Accept World Hypothesis
All Reputation comes from accepted answers and accepting answers. Eventually, one of the First Users either accepted enough answers or got the accept check enough for them to be able to upvote others. And thus could bestow this power upon their descendents.

A:

It's called "bootstrapping."  All new SE sites have lower requirements that allow newer community members to vote on posts until a critical mass is achieved.  This was also true of Stack Overflow.

