Are there literally thousands or is the not hyperbole purely in the every single? And does this include rando extras or just people or some significance?
Literally thousands of related nobles, yet not a single servant or peasant of unknown genealogy? Do all these thousands manage to have their relationship to someone actually mentioned? - I'd have thought with some randoms - we wouldn't particularly need to know one way or the other.
Servants and peasants aren't important, I've only named a few and even then it's since someone in that family is famous today. Plenty of characters have unknown genealogies, but there are a lot of people.
I'm confused by "plenty of characters have unknown genealogies" compared to "every single...character that appears in my novel is related to all the others in some way."
Relation to main character in order of appearance in the first two chapters : 1- Father 2- None (none to anyone) 3-Aunt 4-Mother 5-Sister 6-None 7-None 8-None 9-Father's cousin 10-Father's cousin's wife 11-Father's cousin's son 12-Father's cousin n°2 13-None 14-None 15-None 16-None 17-None 18- 2nd cousin twice removed 19- Mother's cousin's father-in-law 20- Great-uncle 21- None When in those days you have plenty of people with 10-12 children who are princes and princesses, and they each marry other princes and princesses (or kings), you quickly get related to everyone from what I can tell. A SINGLE man married a Saxon woman, linking every character related to that man to every Saxon related to that woman.
In that case, I don't think people will be put off by the fact that all of your characters are related to each other. - because they aren't.