Human biodiversity is a fact. Our personalities and abilities have a significant hereditary component. One quality in which we differ from each other is agreeableness. Low agreeableness is a trait that itself is a source of variation as it makes a person want to resist any type of pressure to conform.
What is the core of our being? In my view, no such thing exists. We are layers upon layers of mental patterns, informed by varying degrees of genetic predisposition, external pressure and habits. At the core, there is nothing at all.
There is value in individuality. Paradoxically, society and not the individual is the greatest beneficiary of individual variation. Most of the time, inability or unwillingness to conform spells nothing but trouble to an individual. Individual variation is essentially nature's way of ensuring a species will not run out of variation for selection to operate on to maximize adaptability.