The history of whether people are - or are meant to be - essentially the same, or essentially different, is a matter of metaphysical assumptions and cannot be determined from observations and evidence -- although observations and evidence may be more, or less, consistent with the metaphysics - in different times and places.
(Men and women, and people of different ages, have always and everywhere been regarded as qualitatively different, at least in this mortal life - until 'officially' the-day-before-yesterday, in a few Western nations...)
From what I can gather of hunter-gatherer spirituality; they regard each person as different and unique; because an unique combination of ancestors (and perhaps animal spirits).
This is how I feel about people, 'instinctively', spontaneously. Each person that I get to know seems to be unique, with resemblances. There are, for instance, distinct likenesses between my mother, sister, and daughter - such that they are obviously relatives and have an (hereditary, presumably) affinity; but each is a very different person.
So, from this perspective, everybody is primarily an unique individual - but some people have secondary, more-superficial similarities.
In this primal set-up; we assume difference; and explain similarity. For example, similarities may be explained in terms of innate attributes (intelligence, personality, size, strength...), heredity, or having had similar experience.
Traditional religions in agriculturally-based societies posit a very different set-up, however. Such societies tend to regard groups of human beings as having an essentially-identical nature, and from this assumption of sameness they explain differences.
This goes-with - although not entailed by - the idea that souls are created from nothing at conception - i.e. because souls come into life with no baggage, it is easy to think of souls as starting-out this mortal life identically; only gathering differences throughout life.
All people may be regarded as essentially the same in origin, or they may be divided into groups such us Us and Them, or castes - aristocrats and peasants, for instance.
Perhaps more exactly, in agrarian society there is an ideal of sameness.
For instance; all priests, or all members of a religion, or all citizens of a nation, may have an ideal type toward which they are encouraged to strive; and from which departures are disapproved, and perhaps punished.
In such religion; it is often stated or implies that Men are created the same, and differences emerge later; and again in the afterlife there is either an identical state for everyone (Sheol, Hades), or else categories of particular people (Valhalla for warriors, saved and damned) within-which there is a single ideal type.
Traditional Christian Heaven is often depicted and imagined as containing hosts of angels, and of the saved, with little or no differentiation between the individuals - as if ideal Men have returned to a primal and intended sameness.
In modern society there is an incoherent mess on this issue, as about most things of importance; and I will not attempt to summarize the contradictory nonsense that constitute feminism, or the official views of homosexuality, or the transagenda.
These are all destructively-motivated power ploys and PSYOPS - not attempts to describe reality.
In brief, modern society demands total sameness - but the sameness demanded varies according to time and situation. On Tuesday race divisions may be treated as mandatorily homogeneous and primary, but by Thursday it may be about the need for sameness among (biological) men and women - while by Sunday the demand for sameness may related to chosen-identity of men and women.
Overlaps and contradictions between mandatory beliefs are ignored, because the requirement is for obedience to arbitrary whim. More more obviously arbitrary and dishonest the requirement for obedience; the more deeply corrupting such obedience will be - which is the purpose behind it.
What is important is that - at each momentary demand to regard X and Y as the same - there be total-obedience to the asserted opinion.
I regard the fundamental truth to be that we are all different in origin and as far back as we existed (which is eternally), and sameness is something either imposed or achieved.
In traditional society sameness was mostly imposed; and in modern society likewise, with respect to those areas in which the rulers wish the masses to be the-same: eg in terms of obedience to Litmus Test issues.
The situation is that difference ought to be taken for granted, because it is innate; yet at the same time both traditional and modern societies depend on treating groups as de facto identical. So there is an innate tension.
The modern idea of wanting to be, and displaying, personal difference; is a consequence of society imposing sameness on what are in fact fundamentally-unique individuals - and this desire typically emerges at adolescence, when the child is psychologically detaching from parental control.
The adolescent therefore feels this innate tension between actual individuality and imposed uniformity most keenly.
In traditional societies the adult role is more of an externally-imposed 'stereotype' then childhood; and innate individuality rebels against this artificial uniformity. Adolescence is a short phase during which the child is channeled into one or another of the 'uniform' and finite adult roles, as demanded by society.
Modern ideology pretends to support individuality against this channeling, but actually demands uniformity on key (destructive) issues. The stereotypical roles have been subverted, demonized, and indeed eliminated.
The consequence is a psychological state of perpetual adolescence - with all the contradictions that implies. The adolescent cannot grow-up, and doesn't want to.
So we get the result that all means of large-scale and and coordinated societal organization tend to - indeed must, operationally-speaking - treat individuals as groups, as categories, as all-the-same. But underneath this is the experienced fact that - when we get to know people - they are all essentially different!
People then feel that they need to assert individuality; and (since these are social-functions) the asserted individuality gets channeled into a finite range of fixed categories...
Leading to the absurdity of standardized patterns of 'rebellion', standard 'rebellious' fashions and behaviours - yet all being claimed as 'self'-expression!
I find that I continually need to remind myself that we are all unique individuals, and that therefore - in an ultimate and spiritual sense - we each will have an unique destiny in a world created by God, our loving parents - who regard us each as uniquely as all good parents do of their children.
A good parent does not want all his or her children to end-up as identical; but for each to fulfill his or her own specific destiny.
A good family is not held-together by externally imposed uniformity; but by he mutual love of its members, all pointing towards the same loving future in harmony with God's creation.
We begin and (after resurrection) end as real, unique, individuals; and Heavenly harmony is an achieved product of love - not a state of of imposed uniformity.
Of course, the defects and practicalities of life on earth mean that this ideal is not attainable on a large scale, or permanently.
Nonetheless, the ultimate reality of individuality is worth remembering, and that harmonious cooperation of individuals is something striven-for not spontaneous...
But that the harmony of love is a higher, and happier and more creative, form of cooperation that the imposition of sameness.
We can thus experience Heaven on earth - but not permanently nor continuously. But that experience can (and should) motivate us towards inhabiting Heaven after death.