I personally feel that since it is taking place during the stone age, and most modern languages don't even exist yet, there can't really be any character development and it won't be interesting to listen to characters interact.
It is not body simply body language. Actions speak louder than words. Have you ever tried watching an anime without the subtitles on. The characters traits come through even without words we know being said, and that is assuming they will not speak. If we can't understand it we can still here the tone which can tell more than words can sometimes. Even that is assuming the characters will not speak English which I'm fairly certain will not be the case. That being said I personally think story is better when it is shown and not told. The other Far Cry games have been guilty of telling you and not showing you so I put forth Far Cry Primal will be even more interesting than the other Far Cry games. Thank you.