"Circa" was not invented. It is a classical Latin word meaning "about" or "near." Because classical Latin was used in many European writings until the 19th century, and even later, the word continued in use with that meaning, even when the rest of a statement is in English.
circa
Concrete was invented by Romans in circa 1243 A.D.
It looks like Jim Ward invented circa 1975.
The citizens of Mesopotamia invented it in circa 3500 B.C.
Asbestos
Paul Really Circa 1742 and Thomas Crapper
While it is commonly believed that Galileo first invented the telescope, it was first invented by Hans Lipperhey, a German "spectacle" maker, circa: 1595.
The first recorded usage of the hyphen is attributed to Johannes Gutenberg of Mainz, Germany circa 1455.
Assuming you mean the first to be made permanent, that would be Joseph Nicéphore Niépce, circa 1826.
The sport of the discus throw dates back to the ancient Greeks and the first Olympics circa 776BC.
There is no such currency as the 'circa'. 'circa' means 'approximately'.
The Greeks are assumed to have invented the first known computer circa 100BC, a mechanical analog computer for astronomical calculations assumed to be used as a navigational aid on ships.