Rechan said:
Interesting notion, but the problem comes from the fact that in a fantasy world, more humans kill more giants or dragons than ants kill humans in our world. With the right conditions, ants could kill a person. But it's a lot easier in D&D for four humans to kill a giant.
We're not just some pesky bug that wanders in to eat their food. We're coming into kill them.
Good point. Perhaps it's not "Human is to Giant as Ant is to Human" but something more like "Human is to Giant as Rattlesnake is to Human." Still, even then, most of the same argument applies. Rattlesnakes are dangerous. Why haven't we killed off or enslaved all the rattlesnakes? Why don't we make sure they understand that we are their masters, and they live or die, prosper or suffer, at our whims?
Because it's a flat out waste of time, that's why. Giants and dragons are going to think much the same way. I, for example, care about having a place to live, food to eat, disposable income, a happy wife, entertainment, etc. All of those things I'm far better suited to get myself than to try to coerce a bed of rattlesnakes into doing it for me.
Furthermore, humans aren't trying to kill the giants or dragons. The vast, vast majority of humans, elves, etc. are too scared of them. It's only the PCs that are trying. They're likely the only group in a century to have even begun to try to kill them. How often in a campaign world do the PCs descend upon a dragon's lair, only to discover that they get there at the same time as another adventuring party, and that both parties are too late--a third party came through, killed the dragon, and made off with the loot. There's another dragon on the next mountain range to kill, if you hurry, but there's already a fourth party on the way. That doesn't particularly happen in most worlds.
Even then, in a world where humans are systematically wiping out the dragons, we can't truly say that one race rules another. Consider bears in a stream, catching and eating salmon. Do the bears rule over the salmon? No. If there are more bears and fewer salmon, so that the bears fight amongst themselves for the salmon, then do the bears rule over the salmon? No. Change it to something like lions and wildebeests, and rulership still does not change.