"They had had a long battle with what looks to be hundreds of participants and there were a few wounded, but nobody died."

Observe the weapons. Most of them are sharpened sticks and they had a limited supply. Less deadly than swords and no mass manufacturing of weapons either.

The spears would be lucky to penetrate the ribcage. But they could go through the gut or throat, and if they were embedded in a thigh, they could easily cause sepsis.

You can easily kill someone with a fire-hardened pointed stick or a wooden club, if you really want to. I think it is just that they don't want to.