[quote=@Spawnling]
Merely existing would require her to grow and adapt, this is basic psychology, and while you mention using human terms for non-human beings, she is fundamentally a human in terms of mindset if she was human once.
[/quote]

Most ghosts, who have been her primary company with very few human interactions, are really stuck in the past in terms of their ways of thinking. Child ghosts, even from decades or centuries past, still act entirely like they did when they first [i]"died"[/i]. To begin with, the essence of being a ghost is of being [i]"attached to the world, but not belonging to it"[/i]. 

You say that she would [i]"have to"[/i] grow and adapt, but that's just straight up wrong. Growth and adaptation are triggered due to a need to progress, due to adversity, or due to willpower to succeed. Ghosts experience none of this. There is no consequence for anything they do, they have no desire to move forwards or accomplish real goals. They're just shadows on a screen, remnants, imprints of a once-living soul left on the world, doomed to wander for an eternity or until they cease thinking. Whichever comes first.

You are saying that in a picture of a small girl, she should age over time. You are applying the psychology of living things to something that is not living. Do you see why you're wrong?