The invisible hand in markets is a natural property with an effect that's dependent on the environment the market operates within. He may be the first person to describe the process in writing (that we know of), but human beings have been experiencing the effects of this since we first attempted to trade with one another.
AFAICT this is (like a lot of the modern mythology of capitalism) started as a response (in the sense of an attempt to build a similar-but-opposed structure, not a response in conversation like a rebuttal) 19th Century anti-capitalist critics (and, in particular, Marx), part of which was setting Smith up as the preceding and opposing figure; a kind of capitalist Christ so that Marx could be the anti-Christ.
