Good post, Silveras. I think another thing that adds a lot to the idea is not to make humanoids have one, single, monolithic culture. Make them as varied as human cultures, with multiple nations, but do so without splitting them into subraces! To me, that adds a great deal of verissimilitude.
Yaar! `Tis true! Yet most of `em demihuman land-lubbers hardly come aboard and sail the seas, yet there be human mates aplenty on deck![/pirate]
Along a similar vein, humans (who rarely are broken into subraces, stat-wise) have a plethora of different deities & pantheons, yet the demihuman races (and their component subraces) are often lumped together under 1 or 2 pantheons. If anything, these demihuman subraces come closest to practicing monotheism than humans.
IMHO, either each culture, human or not, should have a complete, filled-out set of beliefs/mythology (i.e., their own pantheons), or (my preferrence) the number of deities altogether should be reduced. Dragonlance sort of did this, but it doesn't have to be executed in the exact same manner. Essentially have 1 pantheon of deities that are worshipped by mortals, esp. if the deities often interact with their flock through emmisaries (outsiders) or contact (omens, speaking with mortals directly or in disguise, etc.). Different cultures may have different takes on the deities, and may even gravitate to worshipping one particular deity (or set of deities) over others, but the divine powers remain the same.
Then again, a lot of the D&D setting religious rely on some sort of theism instead of using other varieties of religious belief, but that's a whole new thread in itself.[pirate]
Yaar! Blast the land-lubbers and their soil-soled gods! May Neptune calm the seas and Jove blow a strong wind t' catch me sail!