Rewatching episode 2 while watching jax more closely makes me think he really DOES add a key dynamic to the group. Pomni is totally miserable and numb to her surroundings until Jax throws her out of a moving truck. Ragatha is trying to cheer her up in basically every scene, but fails each time. Jax finally just cuts her off and throws Pomni into the middle of the action. It might seem like he's just being a dick, but he immediately protects her with the shoezooka when shes about to get grabbed.. If he only wanted to watch "funny things happen to people" why intervene?
Jax doesn't bother with ragatha or kinger, he lets them just be passengers. Pomni is the only one he forces into playing the game. Maybe he just wanted to see what she would do. But I think this was his way of showing the noob how to adventure properly. Which is directly juxtaposed by the funeral scene, where the others show pomni they are still people and care about each other.