And here is Middle English, from the late C14th. It's recognisably "more English" but still sounds continental.

YouTube- The Canterbury Tales Prologue in Middle English

Quote:

Hwæt! We Gardena in geardagum, þeodcyninga, þrym gefrunon,hu ða æþelingas ellen fremedon. Oft Scyld Scefing sceaþena þreatum,

Thank you for the examples, contra. Unfortunately my French is rudimentary in the extreme and my German nonexistent, so I have no idea what this means. My first wife studied two semesters of Old English and two of Middle English, compulsory components of the English Honours course that she took. While we did not sit around the dinner table chatting in Norse, I have had some exposure to the matter.

Wikipedia gives an example of Old English with a modern translation here. So I asked Google to translate the English into German. Here is the Old English:

Syððan wæs geworden þæt he ferde þurh þa ceastre and þæt castel: godes rice prediciende and bodiende. and hi twelfe mid. And sume wif þe wæron gehælede of awyrgdum gastum: and untrumnessum: seo magdalenisce maria ofþære seofan deoflu uteodon: and iohanna chuzan wif herodes gerefan: and susanna and manega oðre þe him of hyra spedum þenedon.

And here is the Google German translation:

Und es geschah hernach, dass er während jeder Stadt und jedem Dorf ging, Predigt und zeigt die frohe Botschaft vom Reich Gottes, und die Zwölf waren mit ihm, und einige Frauen, die von bösen Geistern und Krankheiten, Mary geheilt worden waren genannt Magdalena, von denen sieben Teufel ging, und Johanna, die Frau des Herodes Chuza Steward, und Susanna und viele andere, die ihm von ihrer Substanz gedient.

Not exactly two peas in the same pod.

Of course German has probably changed as much since the 11th century as has English so this does not bear well on the question of whether an 11th century Brit could intelligently converse with an 11th century - what? Germany was not even a country then and there was no German language, as such: there was a bunch of dialects, some speakers of which might have understood "Hwæt! We Gardena in geardagum", others may have not.

Contra, you may have a very good case to support your claim, but you have not yet presented it.

This is the internet. I can't "prove" anything to anyone who determined to remain unpersuaded.