Hmmm, well, that is a tough call. French is much older than English (and certainly much, much older than "American English.")
If I recall correctly, William the Conquerer introduced French into the language in the mid 1000s. If one wants to see what our beloved language looked like before William's (yes, first name basis ) impact, take a gander at the works of Chaucer, though he technically lived a bit later (approx 1400), and is known as the father of "English literature" (anyone up for a good read of Canterbury Tales? Now THAT is a hard 24 story collection written in "Middle English." Yikes. Hardest 15,000+ lines if it's one's first introduction to English literature.
Of course, we insist, even to this day, to ascribe English words to manuscripts from Chaucer.
ANYWAY, digression: I agree on theater, not theatre.
I've read that Churchill found reports he had to read from American sources to be distracting because of spellings of "theater", etc. It was a pet peeve of his.
Of course I was being a bit facetious about France. But your post reminded me that supposedly, the backwoods accent and speech patterns of the "Carolina Redneck" remain the closest to how Elizabethan English sounded. So I've heard.