I think he’s trying to argue that orcs, golblins, werewolves and undead are still ‘light’ mythical creatures. I don’t see a problem with your suggestions, but they I also have to say that they take away the gritty, medieval feeling if you think about it. Most of your suggested creatures are based in greek mythology for example.
However, the definition is wide open, as the banners available in the game also suggest interesting fable creatures. I think it would be cool to have some kind of ‘Drowner’ type of enemy as Witcher and Warcraft have it. Slimy, fishy folks hiding out in the swamps, praying on poor travellers.