Modern english word emerges at the start of when modern english started to develop shock.
Modern English (sometimes New English or NE as opposed to Middle English and Old English) is the form of the English language spoken since the Great Vowel Shift in England, which began in the late 14th century and was completed in roughly 1550.
The words probably WERE invented around that time. But it doesn't mean that there weren't alternatives for the same thing prior to that.
The language changed significantly in this era, with dropping letters from the alphabet to make 26 being a good example of the extent of the change. Spelling was unstable because of the high illiteracy rates and because printing hadn't been invented yet in Europe, so mass reproduction wasn't possible.
English has been relatively stable, particularly in the last 300 years, because of print become widespread and required the establishment of standards so everyone could understand - and because we stopped getting invaded!