Hey there! I love talking about English so this will be fun. Your question really has two parts:

1. What were the attitudes towards the Anglo-Saxon language by the Norman conquerors?
2. How did swear words evolve in the English language.

I am going to skip over pre-1066. The Kings of England before that time were all Anglo-Saxon and would have spoken Old English (the language of Beowulf and The Holy Rood). This language did descend from the proto-Germanic tree. I will link some texts at the end so you can see examples of what it looks like. It had many different or additional letters and different pronunciation.

It is true that William the Conqueror would have mostly spoken a dialect of Old French when he became king of England in 1066. However between that time and 1362 less is known about how people approached the differences in language. What we do know is that court and the nobility would have primarily spoken this Old French as their first language and much of the official business done in Latin. There are some records during this gap that suggest the kings were learning English but not speaking it as their first language. In 1362 Parliament ruled that official business would be conducted in English and that act signals the real shift to the merging of these languages. At this point it is safe to say that English was not looked down on because it was what was spoken in court. Henry IV would learn it as his primary tongue through the 14th century.

But alongside this we do have two classes. In England there was the nobility who were wealthy landowners that were rewarded with titles by William the Bastard for helping him conquer and claim his throne in England. On the other hand the vast majority of farmers and skilled craftsmen and everybody else would have spoken old English even after the shift in dynasty. But these two languages were merging. Eventually they would combine into Middle English (think the Canterbury Tales and Sir Gawain and the Green Knight). This would again take a leap forward and become Modern English (think Shakespeare) in the 16th century. Since then, thanks to dictionaries, our language has not changed much. I know that was more the adventure of English than you were hoping for but I hope it contextualizes the next part.

Curse words have always existed in our language. Less is known about the origins of many of the curse words you have mentioned. We have some records of them being used in texts, but not many. Many publishers did not print books with them for a variety of cultural reasons until even the 19th and 20th century. Many times texts that included these words would start off with the letters then use dashes for the rest of the word ex. f— or s—. The earliest English dictionaries did not record these curse words so we do not have that valuable historical perspective on the words either. But there are instances where they were used and we can tell that most of the words come from Old English and naturally evolved liked all words to what we use today. Damn is a notable exception because it comes naturally from the verb Damn which has been used regularly to mean someone’s doom or judgement ex. judgement of the damned, “I damn you all to hell!”

There were some more common curse words used in English in the early Modern period that were very popular in literature based around God. God’s Blood, shortened to ‘sblood or God’s wounds, shortened to ‘zounds, were very popular. Calling on the Christ’s Passion was used in these contexts as an extreme exclamation similar to how we would yell fuck today.

I think for further reading, check out the etymology website where they will go into detail about each curse word specifically. They also do a great job in showing in historical texts how it was used/spelled.

TL;DR: Norman kings only spoke French so yes there was a huge linguistic divide and probably wouldn’t curse in OE. Most curses are from OE but not many traces of them. Other curse words were more popular in literature.

Sources and Further Reading: Old English version of Anglo-Saxon Chronicle: notice how dissimilar to Modern English https://www.bl.uk/learning/timeline/item126532.html Middle English Chaucer with translation: https://sites.fas.harvard.edu/~chaucer/teachslf/gp-par.htm Samuel Johnson’s Dictionary: https://johnsonsdictionaryonline.com This is the book to get about English : https://www.amazon.com/Our-Magnificent-Bastard-Tongue-History/dp/1592404944 Etymology https://www.etymonline.com/search?q=fuck Podcast about English Language https://historyofenglishpodcast.com