A couple of points:
The concept of earlier 'civilising' White Gods was common to more than one Sth American culture-- amongst others- and is largely responsible for the viability given to this notion by later "LC"-ers. The most well documented case, as you would know, being that of Cortes' conquest of Mexico- Montezuma assuming him to be their returning[ white ]god Quetzacoatl. It was this belief that paralysed the will of the aztecs initially.
The second point is that few these days would regard the Conquistadores as a superior or 'civilising' influence- they were to a man 'serial killers', who slaughtered at the behest of a priesthood serving some quaint God who had his only begotten son crucified to atone for the sins he himself implanted in us congenital delinquents- hardly the stuff on enlightenment; the only superiority the Spanish barbarians enjoyed was one of superior firepower[ though one must acknowledge that the Aztecs themselves were not an altogether innocent race ].
And lastly, we do have an accurate record of the most recent 'conquest' of a continent- Australia:
The white invaders did not at the time consider themselves a 'civilising' force- they were afterall dumping cargoes of convicts as far away from home as they could possibly get. But they did in due course implant the accoutrements of a separate culture- writing, farming, domestication of stock and of course, a permanent architecture- the only housing ever undertaken by the locals was a single slab of bark against a pole called a mia-mia, a simple protection against the prevailing wind.
Now I think it is possible to argue dispassionately that after 60,000yrs of habitation on this continent, the local aboriginals were never going to construct a Sydney Opera House, or a Harbour Bridge; they had other priorities.
Their culture was one of living in harmony with nature- as opposed to the colonisers whose imperative was to impose their will on the land and all its resources. It is difficult to suggest one of these imperatives as being superior to the other- they both bring a richness of awareness to their practitioners- albeit diametrically opposed in motivation.
[ The resultant interchange of these two cultures after a couple of hundred years is mixed in advantage: certainly the indigenous peoples have lost out in habitat, in health, in identity...., but increasingly many have learned to adapt the introduced customs to advantage- contemporary aboriginal art is increasingly recognised around the world as being perhaps the most vital movement anywhere; there have been similar innovations in music- and an actor who has won an academy award. And there is belatedly a recognition by the descendents of the colonists that the indigenous culture- its mythology, its arts, and particularly its relationship with the environment, is something that must be preserved for own joint cultures to remain sustainable ].
The concept of colonisation anywhere as a 'civilising influence', is I would agree, a condescension, is potentially racist;
but to suggest, after an impartial and objective study of all the available evidence, the possibility of a proto-culture somewhere in the mists of our unrecorded past giving rise to similar developments in architecture and beliefs in diverse parts of the world is . to my mind, in no way RACIST.