Andrew, as I read your post, I wonder if you have thought to see all this as relational, not as an abstract concept. James is teaching an anthropology of Christianity, that is, how we relate to one another. Can you think of all the people in your family circle, the workplace and your social life and how you relative to them? Do you ever think that you would like to have x’s singing voice, or career, or social acumen, or intellect, or goodness, or spirituality or whatever, etc.etc.etc? Now, it is important to remember that so many of our desires are totally harmless, until they result in rivalry which can lead to conflict. Have you ever felt rivalry or resentment towards another? Do you ever feel dislike towards another or are irritated by someone’s behaviour or opinions and have not asked yourself why this person is pushing your buttons? All of this is the intricate web of desire that we live in, and of which we are mostly unaware. It is also extremely difficult to allow ourselves to be loved. But God is not judgemental, we have been taught of an angry, judgemental God, we it is we who are angry and judgemental.
Then there is positive mimesis, to desire or imitate good qualities of someone, as in Imitatio Christi, imitate Christ or the good. We really find God in the other. Does all this make sense?