The Archer is not the first ranged unit in the game anymore - it is the second, after the Slinger. It is a considerable upgrade from its predecessor - it has better CS, better RS, and most importantly, a range of 2, which allows it to hide behind the front line while shooting. However, this unit requires Gold maintenance, which the earlier unit doesn't.
The Archer is an indispensable upgrade for those that seek early combat, or have serious Barbarian problems. What's more, its development is easy, and upgrading your Slingers costs only 30 Gold per unit.
Historical Context Edit
Another hunting tool that proved very effective for killing other people, the bow as a weapon was perhaps first used in the Paleolithic Era. Archery was likely developed in several places more-or-less simultaneously, and except for Australia, it was used on every continent by all sorts of primitives. Until the advent of gunpowder, and even after in some cases, it was the primary light projectile weapon. Not much good for melee though; therefore archers were usually integrated or protected by heavier infantry, the first combined-arms formations in the history of warfare. Over centuries, archers became more specialized, eventually requiring years to become experts at their craft. But most civilizations had elite archery units that could dominate a battlefield under the proper conditions – such as against mired heavy knights at Agincourt, or bare-chested berserkers at Stamford Bridge, or the misguided troopers of the Seventh Cavalry at the Little Big Horn.