Since I won't be peeking at either of those sources, it will be interesting.
By appearance, I would say the creature is more Monstrous Humanoid than Giant, but by habits, abilities & saving throws, more like a Giant. So I think I'll make him a Giant, but so distantly related that he doesn't speak the Giant dialect. This guy seems even dumber and more feral than the Cyclops in the Odyssey, so it shouldn't be much tougher than making a Beast.