including ancient -- several thousands

Nobody actually knows. I've seen guesses in the range of 6,000. Wikipedia, in the article "Lists of Languages," says "_Ethnologue: Languages of the World_ is an annual reference publication in print and online that provides statistics and other information on the living languages of the world. It is the world's most comprehensive catalogue of languages," and that it "lists over 7,100" languages. What is shocking to me is that, in addition to those, there have been _over a thousand_ artificially constructed languages like Esperanto.