The same thing should apply to all creatures, even Digimon and especially villains. If you're going to put your villain as a Complete Monster, then give the backstory to explain just how much of a complete and utter disgusting creature it is, human or otherwise. Otherwise, the villains need the depth and extremeism and gray shades that apply to your regular characters.
There are so many types of characters it's insane. Just like there are many different people in the world. Thinking of that makes everything seem different. It makes it slightly easier. Perhaps that's the issue. Writing's more complex than it first appeared and it takes some getting used to.
Sorry I don't have much to say.
What do you look for in a story? Quality or quantity? Do you like plot twists, sudden reveals, do you look for certain protagonists/antagonists?
Here was the next set. I'll answer them when I have more time. For now SS has the floor. :D