There is one centrally important reality about humanity in Scripture — God made humanity in His image and likeness (Gen 1:26-7). As such, humanity has a special role within creation — we are God's representatives to creation and we represent creation to God. This is why when Adam and Eve fell, they took the rest of creation with them.
Thus the Lord God said to the serpent, "Because you have done this, you are cursed more than all cattle, and more than all the wild animals of the earth. On your breast and belly you shall go, and you shall eat dust all the days of your life. I will put enmity between you and the woman, and between your seed and her seed. He shall bruise your head, and you shall be on guard for His heel.
This special role within creation still exists despite the fall. God has set up humanity in an adversarial role against the Adversary himself. He has given us the power to lift creation up to God — away from nothing and into life. As the personification of that nothing, the devil and his minions will try to lead us to pull creation back towards nothing. Since we have been endowed with the image and likeness of God, who is ultimately free, we have the freedom to choose which path we will follow.
When creating a fantasy RPG where their are a plethora of fantasy races from elves and dwarves to goblins and lizardmen, there arises a conundrum: what, exactly, is "humanity?" Or, more precisely, who is endowed with the image and likeness of God?
This can be handled in a number of different ways:
- All fantasy races are not human and play, to one degree or another, an adversarial role towards humanity. In terms of an RPG, this works better in a Sword & Sorcery-type world where players are going to have exclusively human characters.
- All fantasy races are human. The various differences in races have come about because of some expression of magic. In a world where sin can manifest itself physically, an orc represents humanity consumed by hate and violence. Half-breeds are easily explained in this manner. Worlds using this model allow players to have characters from a wide variety of fantasy races.
- All fantasy races represent the children born of the Nephilim and human women. This choice falls somewhere in between option 1 and option 2. In this setup, fantasy races all have a dark beginning and are more apt to side with their demonic origins than a normal human. As such, players would be free to play the exceptions — those that embrace their human origins as opposed to their demonic one. To a greater or lesser degree, these races would face distrust and prejudice from their human neighbors.
Each one of these choices has consequences in terms of moral dilemmas that will face players. Option 1 allows more freedom for players to slash their way through a bunch of orcs with little or no qualms — they are physical expressions of evil that need to be eradicated. Option 2 muddies the water quite a bit. Killing an orc is the equivalent of murdering a human being. Option 3 similarly muddies the water; however, this can be tempered by how one sees the choice of following the demonic or human path for fantasy races. If this choice is ongoing, than killing an orc is murder. If following the demonic path represents a choice where there is no going back, killing the orc is closer to option 1.
As you can see, there is quite a bit of flexibility in how to represent humanity in a fantasy setting — none of which requires a polytheistic world view.