Language changes. The factors in the change range from new words coming in from abroad and influxes of immigration giving new idioms and flavours, the natural propensity of the human brain to simplify spellings to match pronunciation and simple mistakes which by usage or disinterest in rules, become the new rules. Whatever the reasons without redaction Shakespeare would be hardly intelligible in places and completely foreign in others to modern English speakers so the changes don’t take more than a few hundred years to evolve quite a distance which, since we know every generation of teenagers makes their own contribution to difference, shouldn’t be a surprise.
Research into all the European languages derived at least one hundred elements that are thought to be a proto-language, dating back thousands of years, but giving us a small vocabulary that has left its presence amongst modern languages. Given that Sanskrit is close to Latin those words may even stretch to other parts of the world.
Of course we will never know for sure what words were first, though we can make intelligent guesses, but even if they were simple words of no great moment or thought their existence was mighty. No invention of the brain will ever match the incredible leap, the wondrous possibilities, the important strides that were built upon those words.
We would be nothing without them.