I don't see any N at all in her personality.
She's entirely grounded and not ethereal... not xNFJ in the least. Etherealness is one of the primary qualities of NF... and especially xNFJ, although INFJ sometimes seems very grounded and can look ISFJ in how they behave.
Bottom line: Neytiri acts in the real world entirely and not in abstractions. She responds physically to things, she does NOT abstract first and then choose how to respond.
I'm not sure what else there is to say.
Maybe your other read needs rethought as well; I've never seen that movie, so I couldn't say.