3) "all of us would have been serfs ... that was the vast majority of history"
Serfs are not part of the "vast majority of history." Quoting now from Wikipedia, "It was a condition of bondage which developed primarily during the High Middle Ages in Europe and lasted in some countries until the mid-19th century."
You started in Henry VIII. There were few serfs in that era. Go back in time, and there were certainly more. Go back further and they didn't exist at all.
There were rough equivalents, certainly, but slaves, serfs, indentured servants, etc. are all different. During feudal England, serfs were also different from villeins or smallholders, though all were peasants. (See https://books.google.com/books?id=ax0ed_OEzvwC&lpg=PA49&ots=... for an example of a town with "about 90 villeins and smallholders, plus about 9 serfs or bonded labourers.")
I can accept that you mean to paint with a broad brush, but the brush should be labeled "peasant" or "slave", not "serf". Modern people do sometimes call themselves "wage slaves", after all, and slavery existed for far longer than serfdom.
4) "you worked as a serf on a manor that the lord oversaw. You didn't see the other manors. ... You probably never traveled [to the town over where your cousin worked]. You might not even know about that cousin."
There is an internal inconsistency error here. The parents of me and my cousin were siblings, from the same parents. If what you say is completely true, then how did my parent and his/her siblings end up on different manors from where they were born?
There were alternatives, even for peasants. Here's the Charter of London - https://books.google.com/books?id=7nBZAAAAYAAJ&pg=PA109&lpg=... . Should someone be in London for a Year and a Day, "without reclamation of his Lord", that person would be granted rights to stay permanently in the city. Increasingly after the Black Plague, there was the chance of buying out one's own bondage.
There was also travel in that era, even for peasants. Perhaps the most popular was to go on a pilgrimage. According to http://www.aromasysabores.com/camino/historical_background.h... :
> In the 11th and 12th centuries, millions of people from all over Europe made pilgrimages to Santiago [de Compostela]. It has been estimated that in the 12th century 10 percent of the population of Europe was involved in making or in some way supporting the pilgrimage to Santiago.
According to http://www.pilgrimisverige.se/att-vara-pilgrim/historia-1727... (in Swedish; I couldn't find an English source):
> Miljoner och åter miljoner människor var ständigt på väg och man har beräknat att mellan år 1150-1450 deltog mellan 20 och 50 procent av Europas vuxna befolkning i pilgrimsvandringar.
> [My translation:] Millions upon millions of people were constantly in route and it's been calculated that between 1150 and 1450 between 20 and 50 percent of Europe's adult population took part in a pilgrimage.
From "Canterbury Tales" we get an idea that people from all walks of life went on pilgrimages. But there's no need to resort to fiction. See https://archive.org/stream/englishwayfaring00jussmiss#page/2... where it says (p 263, and footnote 2):
> .. but in such another county, they heard or supposed, there was better pay an less exacting masters [2].
> [2] See a concrete example of such reports being brought from the north to the south by pilgrims, further, p279.
> [p279] The report had been brought to the city of Canterbury by pilgrims, peregrini, arriving from the North, obviously to worship at the shrine of St. Thomas.
Certainly even serfs had knowledge about the outer world through contacts like this.
And finally, from that same source (https://archive.org/stream/englishwayfaring00jussmiss#page/2... ) we see that the ravel restrictions even at their harshest were not to the manor, as you said, but to the hundred, city, or borough. A hundred is a subdivision of a county and contains several parishes and many towns and manors. It is very likely that you would know your cousin the town over because it's within the same hundred.