How did Safehold's Society Devolve so Quickly?

I have several questions that are kind of tied up in a generational format. For simplicities sake, I'm going to consider a generation 25 years. That would make the ~900 years since the Day of Creation when Nimue woke up 36 generations.

Now, the Adam's and Eve's still had the life extension treatments, and though they weren't receiving the boosters like the Archangels were still lived for an additional 150-200 years after waking up on Safehold before finally dying of old age. During that time, they'd be interacting with 6-8 generations of their descendants. I highly doubt they'd be okay with seeing their children, grandchildren, great-grandchildren, etc. becoming serfs or slaves as became very common planetwide, especially in Harchong.

Now, it is mentioned the Church discouraged literacy for some time, especially after the Adam's and Eve's died off and I can see how with the rise of feudalism the obligations of the farmers (both to a liege as well as tithing to Church) could create financial circumstances leading to indentured servitude and eventual serfdom/slavery but that would take some time. And it is written that slavery and serfdom had been present for centuries. And what would the Church be doing all this time? This would be in the first 200-300 years and corruption in the Church would not have set in yet as it would 900 years later when the books start.

I'm also wondering how Feudalism developed. Typically, Feudalism is a response to some form of threat that requires someone to take charge to protect the people within their realm of influence. What threat encouraged this banding together under what became a hereditary leader? Especially with the Church in a position to oversee everything and prevent events from getting out of hand. Unless the Church was deliberately creating various crisis to facilitate the formation of the great kingdoms. But that doesn't make a lot of sense because it would mean creating a potential competing authority alternative.

Speaking of threats leading to creation of kingdoms, why did so many kingdoms go to war with each other (ex. Siddermark and Desnair). Historically, nations go to war over religion (not an issue), resources (I can't imagine any of the enclaves not being created in a location without sufficient resources), or territory. The thing about territory is the nations are already absurdly large. Siddermark being the size of North America? With so much land not terraformed there should be little to no reason for one nation to attack another. Distance alone should make it prohibitively costly.

In the beginning of OAR Lake Town felt more like an independent town with an elected mayor. Since I believe the majority of colonists were militarily associated, I can see how Bedard perhaps chose officers to be 'programmed' to become noble houses and found various dynasties that formed the various nations.

Just find it odd how Safehold's society developed the way it did so relatively quickly.

Humans are complex and human societies are very complex.
Consider the Roman Empire at say 50 AD. Organised, running water, concrete, steel weapons, artillery, a form of democracy (limited and flawed true), international trade, artists supported by the state, philosophers honoured, even toilet sponges and heated baths, sort of civilised.
Then jump 500 years forward. High illiteracy, petty little kingdoms across Europe, rarely bathing, weapons no better than the Romans, the "Dark Ages".
Being a sort of agnostic/atheist blend I would point to the stranglehold of a highly organised and ultra conservative church as a major culprit. However it is more complex than that. A complex society is a card house, doesn't take much to destabilise it.