Oldest cache of assorted types as far as I know. Types were invented after the caches had existed for a while, and cache owners were able to change types, so determining first for each type is a confused exercise.
Originally, all caches were listed as Geocache.
May 7, 2001, Jeremy added cache types. See this forum thread, Cache Types
Created at that time:
Traditional, Multi-cache, Letterbox hybrid, Virtual, Unknown, Event
May 01, A.P.E. caches, then Webcams (Jan Feb 02), Locationless (April 02), CITO events (April 03), Earthcaches (January 04), MEGA event (May 06), GPS Maze (June 07), Wherigo (January 08), 10 Year Events (May 10), HQ cache (cache from '04, special icon from 10) and HQ Lost & Found event (July '10) HQ Annual Block Party (Aug 11) and Lab Caches (Aug '13).
Good info in this Oct 04 forum thread
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