Indeed, I remember being in Oxford in the 90s and an older man approached me and spoke to me in English and I couldn’t understand a word he said. My ex-wife, who’s an ESL speaker who speaks fluently and without an accent has trouble with English accents in general. Similarly, in Spanish, I find it’s generally easier for me to understand Spanish speakers than Mexican speakers even though I learned Mexican Spanish in school and it’s been my primary exposure to the language. Likewise, I generally have an easier time understanding South American speakers than Caribbean speakers and both sound little like Mexican Spanish. (The Spanish I understand most easily is the heavily accented Spanish of non-native Spanish speakers.)

Accents have diverged a lot over time and as I recall, American English (particularly the mid-Atlantic seaboard variety) is closer to what Shakespeare and his cohort spoke than the standard BBC accent employed in most contemporary Shakespeare productions).

You can try this video to see how far back you can understand spoken English: https://www.youtube.com/watch?v=842OX2_vCic

> Spelling is conventional and spelling and alphabet changes don't necessarily correspond to anything meaningful in the spoken language

On the contrary, spelling is highly idiosyncratic until the 18th century, and until then it was tightly correlated to the sounds of spoken language. Shakespeare didn't even HIMSELF have one way of spelling his own last name. That's how non-conventional spelling was until pretty recently.

You can even see it in these examples, words like "maiſter" in IIRC the 1300s example. Which becomes "master" later in English, but remains Mäster in Frisian (the closest Germanic language to English) and is also mäster in Swedish.

Languages can change in many different ways. Pronunciation changes impede you a lot more the first time you meet someone with a different pronunciation than they do as you interact over time. Grammatical changes are trickier.

Yeah it’s really just the glyphs that are changing here, and occasionally the spelling, otherwise the words themselves are still fairly recognizable if you’re well-read.