The usual way of measuring a trait would basically be measuring N amount of people on a specific thing, and the distribution based on that. But if you take 1 person, and N amount of specific things/traits, just about everyone would probably make their own sort of distribution with a bunch of "normal" traits and a long tail of "unusual" traits.
Still a simplification, but has made the "illusion of a normie" clearer to me.
This is literally true on a physical level: The US airforce did a study in the 1950s that showed none of the thousands pilots they measured matched the average across multiple body measurements. i.e. no one was average.
https://austraffic.com.au/aba/us-air-force-finds-averages-ca...
Edit: the report itself:
https://apps.dtic.mil/sti/tr/pdf/AD0010203.pdf