Hits fully absorbed by armor are registered as misses, so that's most likely what you're seeing. Single archers are only really effective against unarmored opponents. Training groups so they can volley will yield better effect.

You can get shortbows as the third warfare tech IIRC, and longbows one after. I'm not sure what the formula's are, generally I find archers work best in groups - with a party you can virtually guarantee at least one hit. I'd jump for longbows straight off (I don't find shortbows worthwhile) and then get logistics. You don't usually need to worry about armour, because if your archers are in melee they're doing it wrong Some of the magic or miscellaneous items might help though, if you can afford them. I find parties of longbowmen more than adequate to defend my cities until I can start training up some really nasty stuff, and they're pretty effective against the initial wandering beasties too.

I've also had some success equipping my sovereign with a longbow; she managed to snipe a Drake down (though not before he'd wiped out three NPC's and three parties of units). Her attack wasn't much more than 17 or so.

This is just guessing, mind you, but I suspect that the idea is that if you want GOOD ranged damage, especially with your sovereign, use magic.

Still, I do find a combat - Sovereign with a longbow QUITE effective, especially early on.