How far back in time can you understand English?

https://www.deadlanguagesociety.com/p/how-far-back-in-time-understand-english

Passages written in the period, in 100-year increments

“Before the mid 1700s, there was no such thing as standardized spelling. Writers spelled words as they heard them, or as they felt like spelling them, which is why the 1500s and 1600s sections look so alien, even when the words, underneath the surface, are ones you know.”

“As you move backwards in time, the French and Latin loanwords that make up an enormous proportion of the Modern English vocabulary grow fewer and fewer. When you pass 1250, they drop off almost altogether. Where a modern writer would say he underwent torture, a 1200-era writer must say that he suffered pinunge instead”