[AdmiralZhao]

If the archers are firing at heavy infantry with shields, then it is not unexpected to see only a couple of the infantry taking damage each salvo. If you are firing at barbarians or other unshielded and unarmored units, then you should see a many more units taking damage, though you still might not break the barbarians before they reach your lines.

In general, archery isn't that great, since it has a propensity for friendly fire and can be tricked by decoys. It's main use is against expensive, high defense units (Mictlan's Jaguar warriors for example). If you want to kill things at a distance, start trying out the mages!