This was visible even in OD&D once you got out of the most basic classes; things like rangers and druids were always pretty clearly as much about who you were as what you did.
Agreed. After you got past the first two archetypes (Fighter, Magic User), all the classes were about who you were. While we have tried to retcon the other classes in hindsight (the Cleric was just "the original gish," or the Thief was just "the original skill monkey,") that's not accurate. Each was a specific embodiment of an
who you were.
ASSASSIN (
Blackmoor) (originally played by Allan Hammock)
You kill people.
BARD (The Strategic Review v. 2 #1)
A mix of a skald, a bald, and a minstrel.
CLERIC (
Men & Magic) (Bishop Carr first played by Mike Carr)
Based on Vampire Hunters (Van Helsing/Hammer Horror) slightly modified by Gygax (Bishop Odo).
DRUID (
Eldritch Wizardry)
The '70s understanding of the Roman's understanding of the Celts (with the '70s environmental sheen).
ILLUSIONIST (The Strategic Review v. 1 #4,)
Peter Aronson really liked illusions, and wanted a spellcaster that did illusions.
MONK (
Blackmoor)
Brian Blume wanted to be Remo Williams.
PALADIN (
Greyhawk)
Gygax really liked Holger Carlson in
Three Hearts and Three Lions.
RANGER (
The Strategic Review v.1 #2)
Joe Fischer read the new Paladin class, and was like, "Yes, but I wanna be Aragorn."
THIEF (
Great Plains Game Players Newsletter #9)
Originally created to be a "box man" (Wagner/Switzer) and reported to Gygax, Gygax added a few details from Vance and Zelazny (Cugel / Jack) and switched from a spell-slot system to percentiles because Gygax.
I'd argue that
every single class after the original duo was specialized and that the only difference is between classes that were specifically designed after a fictional character (Cleric, Monk, Paladin, Ranger) and classes that were designed to model more general fictional gestalts (Assassin, Bard, Druid, Illusionist), with the Thief being a mixed case.