> This story is a winding one, beginning in 1981. Kermit is, to the best of my knowledge, the oldest actively-maintained software package with an original developer still participating.

This is a bit of a philosophical question, for example, much of the (Lisp) code in current Emacs is from the 70s, but the GNU Emacs interpreter wasn't started until the mid 80s (also ... people weren't great at version control in the 70s, so there's not much actual development history).