It may be worth noting that the transition from Anglo-Saxon to present-day English wasn’t a linear path. Before 1066 there were several language variants in use in the British Isles, of which Gaelic and Welsh are the remaining remnants. After the mingling of Norman French with Anglo-Saxon (which gave us a class-stratified vocabulary), there were many variants of English spoken across Britain. While we think of Chaucer, we need to remember that the Gawain poet (who lived around today’s Wirral district, near Liverpool) spoke and wrote in quite a distinct variant that is closer to the Anglo-Saxon of Beowulf. The generic school curriculum gives a somewhat misleading view of how English morphed and evolved: far from being a linear progression it was a tangled convoluted process that continues to the present day.
Today, the most salient thing to note is that English has branched into several distinct families. US English is the RISC version: three tenses, no subjunctive, no adverbs, a highly restricted vocabulary dependent on phrasal verbs. British English is the antique version: twelve tenses, basic subjunctive, a far more extensive vocabulary but also a far more extensive set of regional variations. Indian English falls closer to British English but has plenty of local modifications (as per, “You are too clever” which actually means “you are very clever”). It remains to be seen how far apart these variants will drift over the coming centuries.
The history and development of the English language is complex and enchanting, and is worth a year or two of study for the sheer intellectual pleasure of the exercise.