Yes, children are trained as squires to become knights, sent off to monastery to become clerics, apprenticed to a mage to become wizards, etc. Most classes at level 1 are modelled on the heroic output of in-game professional training + natural talents. The warlord class has no equivalent in-game meaning and feels artificial and arbitrary in-game (outside of the metagame).
What?
Dude, don't blame anyone but yourself for your failure of imagination.
A 1st level warlord might be the eldest son of a chieftain, robber baron, governor, noble, etc. Brought up to lead men in war.
A 1st level warlord might be a mercenary captain. He might be a mercenary sergeant. He might be a fresh untried mercenary with a bevy of natural talent.
A 1st level warlord might be an old retired centurion called back into service in his twilight years. Not every starting adventurer is a 16-year-old sprig, you know.
A 1st level warlord could be a pretty princess who shouts panicked commands to her bodyguards, friends and allies- never attacking herself, but just directing the flow of battle.
And how many movies or books or comics or tv shows or plays have shown us the image of the wounded hero, seemingly taken out of the fight- until an ally/friend/loved one/commander pleads, "DON'T GIVE UP!!" and somehow, the hero struggles to his feet despite his wounds, given the sheer mettle to keep fighting without closing a wound? Not to mention that being at 0 hit points doesn't have to mean you're lying in a pool of blood with your guts stretched around you.
If there is a problem with the warlord, it is in peoples' unwillingness to stretch their imagination
just the tiniest bit, not in the class design. And really, that tiny tiny stretch? There are tons of examples in pretty much every type of media that will paint a picture of a 1st level warlord... not to mention history. Even as a fresh-faced youngster! Octavian, anyone? For something more modern, how about 15-year old Burmese warlord Mohammed Humayan? There are plenty more.
However, some people have made up their mind that the warlord MUST BE (fill in your vision of the warlord), and therefore it just. doesn't. work.
That's fine; everyone has their preferences. But think about it- if you'll play an elf, you look pretty damn silly bitching about how a warlord is unrealistic.