Modern common sense (and, I suppose, all other societies) explain individuality in terms of heredity and experience (aka 'environment') - in addition to which Christians would underpin these with the fact of having been created by God.
But all of this makes individuality something passively given - on these metaphysical schemata, individuality is merely the mixture of these three elements - creation, heredity, experience - and therefore individuality has no validity in and of itself.
If we are wholly created, we wholly belong to God and individuality is some kind of wicked illusion. We are simply pieces of God - and anything which God (or the Adversary) may have made us feel about this is simply a mistake - there can be no comprehensible autonomy or freedom if we are simply chips off the old block.
And if we are wholly a product of our heredity and experience; since we chose neither, then there is no basis for respecting individuality as significant. On such a basis a grain of sand is individual - in that no two grains are exactly the same - but the differences are contingent, passive, meaningless.
I am therefore of the conviction that a long hard look at the human condition leads to the conviction that if our individuality is to have any real meaning as a fact of existence, it must be prior to creation +, heredity and experience.
(In other words, God created us as Men - but did not create our unique individuality - because individuality in any meaningful and significant sense cannot be created.)
In other words, there must be some-thing - unique to each person - that was not created by God, came before creation by God; and therefore also came before any effect of personal experience or the hereditary influence of ancestors.
This, if individuality is real and not an illusion, then it is something that comes from 'eternity' (it 'always' was) - and that creation to become a Man, and then a Man affected by heredity and experience, is something that happens-to this individuality.
Individuality remains within the created humanity, and behind the effects of heredity and experience.
And this is why we cannot (try as we might - and some people spend the best efforts of their life trying; and some societies expend vast effort and infinite ruthlessness on the job) ever wholly shed the sense of individuality; and why half the religions and nearly-all the human societies of the world have never been able wholly to extinguish it.
So I think it would be a good thing if such a fundamental and seemingly-ineradicable reality of our condition was properly represented in our basic (metaphysical, theological, philosophical) description of things.
+"Creation" in this sense means something like 'organized from existing materials in in accordance with existing constraints' it does not mean creation in zero-time and from nothing.
PS: Take the example of Satan and his choice of evil.
'Mainstream' Christian theology (i.e. the type I think is up-front incoherent) would have it that Satan was an angelic being entirely created by God, and lived his pre-downfall life entirely in Heavenly circumstances which were entirely of God's making and choosing. Where, then, was the evil supposed to have come from - if not from God? And if God made Satan the way he is, then God is responsible for everything that Satan is, has done and is doing - and the same applies to all demons, evil humans and indeed all evil - but this makes no sense.
If, however, it is allowed that there is a somewhat about Satan that was not created by God nor a product of his experiences in Heaven, then the incoherence disappears; because evil was something in the nature of Satan prior to his creation by God.
Furthermore, the reality of free will, agency and the ability to choose between Good and evil (or anything else) has the same pre-creation origin.
So Satan had evil in him not from God but carried-over from his pre-created self; also Satan was able to choose whether to affiliate with this pre-creation evil or to affiliate with the Good, which he had learned about post-creation, from his experiences in Heaven.
Thus, when individuality is regarded as irreducible and uncreated - this makes sense both of the existence of evil (in the context of a Good creation by a wholly Good God); and also makes sense of choice, the reality of which comes from the autonomy of individuality - and the reality of choice is, of course, absolutely necessary to Christianity.