For 2,000 years, the early Britons spoke Gaelic and Welsh. You can still hear these in parts of Ireland, Scotland, and Wales. Then the Romans brought Latin with them 2 000 years ago.
For about 1 6000 years, since the Romans left. Two people invadede Britain from the late 4th century: the Angles, from what is now southern Denmark, and the Saxons. Both spoke Germanic languages which mixed with other Germanic languages after the Vikings invaded in the 9th century. This mixture became Old Emglish.
Only about 15% of Modern English comes from Old English, but it’s a very important 15 % - words like be, get, water and girl come from Old English.
It got mixed with Latin and French languages brought by the Norman invaders in 1066.
This mixture was called Middle English, and it was taught in schools from 1350.
Around 1400, people starter to speak differently. Before this, the word name was pronunced something like “narmer”, and life was “leef”. London, where books were printed in English for the first time in 1476, became the standard model for English, and the first dictionary was printed in 1604.
In some ways, American English is closer to Shakespear's English than the modern British English is, because the first settlers kept their language the same. Words like trash (rubbish in Britain) and fall (autumn) were originally from Britain. The USA also took native American words into the language, like tomato and barbecue.