English vs American Englash

A few people here have said to me "english is pure. americans use english with slang and bad words" with the idea that english in UK is the unchanged original. Evolution of language i've often thought about with relation to Indian english and its 'turn of the century' phrases, or international english as might be spoken between two non native speakers in africa or asia. And ditto spanish here is more formal and rigid than has evolved in Spain, with differences on route between mexico and chile. Bet Shakespeare would have a thing or two to say. Probably incomprehensible to us these days..