A mondegreen, in fact: http://blog.dictionary.com/ampersand/
This blog also discusses thorn and wynn
But they're a little confused:
In the Latin alphabet, the “y” was the symbol that most closely resembled the character that represented thorn. So, thorn was dropped and “y” took its place... That is why the word “ye,” as in “Ye Olde Booke Shoppe,” is an archaic spelling of “the.”
Thorn wasn't replaced by y, it just looked a lot like y. "ye" is not an archaic spelling of "the", it's a misreading. The archaic spelling of "the" happens to look like y with a little e above it.
What about the Latin "I?" Didn't the Romans misinterpret the Aramaic "Yod?" https://en.wikipedia.org/wiki/Yodh I'm thinking of the "INRI" on Latin crosses suggesting that there is no such person as Jesus with a "J."
Apparently INRI stands for Latin
"Jesus of Nazareth king of the Jews"
J is a variant of I that arose relativley recently. The Romans did not have J.
That's the way I understand it. And the "VS" (US) ending would be Latin masculine, so a translitteration that bears no resemblance to the original Hebrew name.
No, apparently Latin Iēsus is "Highly irregular, but often considered to belong to the fourth declension."
It makes sense that it is irregular, since it was borrowed from Greek which was borrowed from Hebrew.