re: Which human being has made the biggest impact on human history?

I'm far from an expert, but the evidence uncovered is from an ancient workers' village. Many if not most of them existed to build the tombs and monuments glorifying the rulers they served, whose rule, as far back as can be evidenced, is based on their connection to or representation of the deities of the day.

But that's language. No one really knows what civilization first emerged. However, since the evidence of gods occur at the same time language appears, it can be presumed this practice had previously existed for a long time.

Religion is the basis for societal unity in both cases, but its origin as such cannot be traced.

So basically, no one knows.