Usually, laziness wins out. I dunno if tagging brackets would be something people would stick with. Maybe if it was so the initial posts served to teach what it means, and then it could be dropped.
Probably only different enough for the enviroment to provide some surprises every now and then and maybe a hidden twist or two for the story. I guess I would have to setup some loose guidelines for the world before any thesauruses can be made. But you don't think it sounds too silly? I guess most words have kind of a basic nature. Onomatopoetic words are another thing, like how can people from different parts of the world have such distinctive ideas about how animals sound for instance.
So what words would a loose clan-like extended family need besides words for hunting, which probably ought include some directions or something. But how does one name a direction? Why is it called left and right anyways. And how does one convey a direction from one observational point that only applies for someone with a different perspective, besides just... pointing somewhere. Maybe stick to pointing...
Oh yeah, so I was thinking, since they're primitive, they probably would have no concept about what causes pregnancies, and as such, they wouldn't have any concept of what a father is. But since it's kinda hard to ignore being birthed by someone, they know what a mother is. And a mother would remember who her children are. So how do you show that someone is your child? You take their head and shove it to your breast, that's what.
So yeah, that kind of physical communication would probably be the most common, grooming, hugging, hitting, shoving. There would probably be a male and a female alpha, basing lots of it on chimps and apes. But I still want to avoid some of the less savory parts of such directness, which is why I feel it's a good idea to not make them physically human.
A few other things to consider would be that there wouldn't be much room for gear and loot other than sharp rock and sturdy club.
So that's worth keeping in mind. The best thing would be if the whole creating the language thing could stand as its own selling point.