In most games, you’ll have some sort of meter for survival. Since this is the paleolithic age, I’ll assume there are some basic requirements. For example, a water meter, which depletes after a certain amount of time, health, and food. Energy would also be applicable to this scenario. I’m sure almost sure that this will be automatically in the game, or similar.
One important one I’d like to suggest is “social”. This wouldn’t be called social, but something like it (reputation?) would work very well. Because it’s a multiplayer sandbox, interaction is necessary. Sharing a shelter, feeding others, etc, will boost your social meter. When you do something unfavorable, you might lose some. For example, wage war, or cause disputes with NPCs in your group.
For attributes, something like speed, strength, and intelligence would be useful. Strength does not go up instantly, you get it passively through working (or in fighting). Speed could be used as an escape possibility, and intelligence to learn new recipes. To enhance your skills, you could either do it the normal way or get a prowess (see other suggestion thread here).
That’s all, hope you like it.