Why is a 1st level fighter called a Veteran, when a 1st level thief is only an Apprentice, and a 1st level cleric is just an Acolyte?
Consider it in terms of my most recent post on henchmen (er...retainers). A normal human that earns any XP from an adventure must choose a character class in which to make a career.
So how is XP awarded? By surviving an adventure (defined in Moldvay's Basic set as a single session of play).
A normal man that survives an evening's delve is a blooded veteran, no doubt about it...if all he wants to do is continue swinging a sword and working on his combat prowess, that's a fine and apt description. For those individuals who decide to pursue other career routes, they have only just begun their path of higher learning.
Besides, even a fighter must achieve 2nd level before he is considered a full-on warrior, and 3rd level before he is a proficient swordsman...and of course "hero" isn't awarded until 4th level.