*Edit: I checked some of the stuff more out in detail. While some concepts on this are valid and backed up by sience, others like RSD are not. Use this as a springboard for learning, not as a valid source in itself. Yes it says so in the corner already. But spelling it out might help.
People are more complicated then a diagram from the internet. Never forget that.
I always think of probability distributions in this context. Taking something like the bell curve for instance. Being bang-on precisely average is actually very unlikely. Some degree of "divergence" or "variation" from the mean is in fact the far more likely state. Even taking the typical +/- 1 standard deviation, which comprises
~68%... that leaves~32%that do not fall into the middle or normal range.That's a huge amount of people that may all be very different from each other, even more different from each other than they are from "the average", but are all very different from "normal". IMO, it's not appreciated enough how much variation is baked into anything statistical.