Yeah, I think even if Griffith is not human anymore, he still exhibits very human desires. This was displayed with the rape of Casca. He wanted to hurt them both because they had a relationship that excluded him. That is pure jealousy. He is still ambitious and calculating. If he did not have human emotions, this would be beneath him. Heck, all of the God Hand members display human emotions. As you pointed out, Flora said they were human once. I think the emotions that are lacking is empathy and love.