So this person is at the top of the social hierarchy, dresses, eats, lives better than everybody else, then their child dies and they shrug and throw the body away in a common grave?
"The full jhator procedure (as described below) is elaborate and expensive. Those who cannot afford it simply place their deceased on a high rock where the body decomposes or is eaten by birds and other animals."
Why are we assuming that the top of a hierarchy must dress better and eat better than everyone else? They could just be leaders who command everyone, but still an assumption of equality when it comes to good.
Also hierarchy doesn't mean that there is a single individual that's at the top. There could be a series of caste hierarchies, where groups of people were considered "better" than others.
We don't know if everyone from the tribe was in the common grave or a select group of people.
You're building a narrative based on your knowledge of other civilizations histories and understanding of modern day social structures, and assuming those traits must apply to this civilization. The truth is, we don't, and likely won't ever, know how their social hierarchy was built. Anything said is speculation. This isn't the case where you can be 80% confident something is true, more like 2% confident based on the discovered evidence.