It is a pervasive and influential - albeit unacknowledged - assumption of most Modern people; that everything, and everybody, has always been the same everywhere.
At most, some who regard themselves as 'realists' (usually supposing themselves to inhabit 'the Right') will acknowledge differences in ability and personality - for instance significant differences in intelligence between individuals, races, sexes; and similar hereditary personality distinctions.
Yet, there is often an extreme reluctance to acknowledge that people in other times and places had a different relationship with 'the world', and were differently motivated*.
The sameness of people is clearly an assumption, that is a structuring and metaphysical assumption - prior to evidence - not a consequence of examining 'the facts'; because the facts can equally 'prove' the opposite when examined on the basis of the opposite assumption: i.e. the assumption that the consciousness of Man has developed through history, and different among different places and races.
Another, and related, Modern assumption is that each individual man is ultimately to be understood as the member of a group (or several groups). This is found in the leftist identity politics which has utterly taken-over the highest level of global leadership - such that an individual is defined by society (and, more importantly, by himself) in terms of group-identification - sex, race, sometimes class, sexual alignment or identity, political affiliation etc.
Consequently, the ultimate goal in human life (or the 'bottom-line' of existence) is seen (albeit vaguely) in terms of gratifying group ideals. Once a person has identified 'itself' by group affiliations; then hopes and aspirations are focused on group arrangements - that is, on social and political arrangements.
There is an ethic that nobody can be, or ought to be, 'happy' unless and until some particular socio-political arrangements are in-place - and this is the basis of the waves of leftist, top-down crusades. It is an absolute and wholly uncompromising ethic - while any particular 'crusade' is active; such that the moral individual must be (in principle) prepared to 'pay any price' to achieve... whatever it happens currently to be... elimination of the birdemic, global antiracism, climate cooling, a massive increase in transidentification, and annihilation of the Fire Nation are recent/ current examples.
We can see that all these share the structuring assumption that groups are primary. The individual has no identity or validity aside from the identity with group - and this has become the prime act of choice.
We must choose our group identity from a range currently 'on offer'; and those group identities which are positively valued are based on inverted values, are anti-natural, and/or subversive/ destructive of whatever Christians would regard as Good.
Group identities based upon self-hatred and a covert suicidal motivation are particularly highly-valued.
Resistance to the mainstream 'offers' and value systems are almost-always also framed in a way that gives primacy to the group; not least because this is regarded as the only way that power can be matched and overcome.
The general idea is to generate Good Groups to oppose and defeat Evil groups - thus people hope (and work) for Good groups based on particular Christian Churches, or particular nations or races - or esle they hope (and work) to 'convert' particular churches/ nations/ races away from evil leftism and to something better and net-Good.
Ad this is done on the basis that Men are essentially (deep down, primarily) the same now as ever we were; and thus the lessons and practices of The Past (of some particular past and place) can be re-animated and re-applied to the Present and Future.
However, if Man's consciousness had changed throughout history, differs in different places - and is, indeed, differentiated down to the level of individual persons - then the world and its prospects are very differently understood.
What this entails (for Christians, anyway) is a structuring conceptualization (i.e. a metaphysical assumption) that God is concerned primarily with individuals, and not therefore primarily with groups - not even with those groups we call churches.
For this to be true, it seems that each individual is likely to have an unique 'destiny'; which he presumably brought-into this mortal life; and which has developed in life as a consequence of choices.
And if Man's Life is indeed to be understood in this individual fashion, then we will also assume that God is 'running the world' in ways that primarily take account of individuals; of individual persons each in a relationship with God.
If so; then the world changes for the better by means of this individual relationship and action.
And, conversely, to regard the world primarily as composed of groups will intrinsically drive the world (and the lives of individuals) towards the worse; whatever those groups may be.
We then cease to seek group-solutions to world problems - and cease to seek group-motivations; or, at least, cease to regard group-level analyses and policies as the Main Thing.
We assume, instead, that The Action is driven by individual persons; and that God's positive interventions in The World operate via the actions of individuals - by the choices, thinking and doing of individuals.
*The largest and most obvious difference is that Men of the past saw their lives and the world (as it were) through religious spectacles; whereas now this is very seldom the case. So alien has this become that many recent depictions of Medieval life are grossly unrealistic in their distortions - either all-but ignoring religion, or assuming that the churches were wholly cynical and manipulatively directed at modern objectives.