If you adjust the number of homicides per capita, tribal wars are far more destructive that anything more modern (including WW1&2). It's hard to get the right perspective on it, because hunter-gatherer societies are so small, the death toll from warfare isn't just a large and impersonal number, but specific people's stories. So then we compare it to our nameless millions of dead, and proclaim ourselves to be monsters. But:

"Anthropologists formerly idealized band and tribal societies as gentle and nonviolent, because visiting anthropologists observed no murder in a band of 25 people in the course of a three-year study. Of course they didn’t: it’s easy to calculate that a band of a dozen adults and a dozen children, subject to the inevitable deaths occurring anyway for the usual reasons other than murder, could not perpetuate itself if in addition one of its dozen adults murdered another adult every three years. Much more extensive long-term information about band and tribal societies reveals that murder is a leading cause of death. For example, I happened to be visiting New Guinea’s Iyau people at a time when a woman anthropologist was interviewing Iyau women about their life histories. Woman after woman, when asked to name her husband, named several sequential husbands who had died violent deaths. A typical answer went like this: “My first husband was killed by Elopi raiders. My second husband was killed by a man who wanted me, and who became my third husband. That husband was killed by the brother of my second husband, seeking to avenge his murder.” Such biographies prove common for so-called gentle tribespeople and contributed to the acceptance of centralized authority as tribal societies grew larger."

As far as I know all this is controversial. Some tribal zones are under nearly constant low-intensity warfare, other know rare but rather sever episodes. In many other areas war is sporadic and each conflict is, by convention, halted after a rather limited event (first wound, first blood, or first death). In at least some cases neighboring tribes intervention forbids escalation (as they have members coming from the tribes at war, or want to avoid unpleasant side-effects, for example arson).

Someone unhappy can escape from a tribal zone, and (albeit not easy) it is much more easy than to escape from our civilization.

In the same vein escaping a tribe or tribal war may not be easy, but one may have major problem showing to me that escaping modern society or modern war (or, worse, a full-blown world war, or nuke war) is more easy.

In our very own towns there are very violent subcultures, composed of a rather high amount of people. Many women living in gang zones have life paths (companions killed, maimed, overdosed, in prison for life...) similar to the ones of the New Guinea’s Iyau women. One may also check the lumpen proletariat, living and dying in IMHO appalling conditions. Is this representative of our civilization? Are those Iyau's women representative of tribal life (in each and every tribe)? Are those last less able to escape than gangzone women?

Each civilization has zones of extreme occurrences of nearly any type of event (here of violence), and at least partially locks people into their present situation.

Studies about the amount of violent deaths in the past are difficult to assess. Some tribe members invented stories in order to satisfy their audience (anthropologists).

What an individual is living (or really able to do) in a given culture is very difficult to understand and represent in another context, as illustrated by Horace Miner's Nacirema 'study'. Not to mention than cultural relativism and moral relativism heavily taint all this. Moreover various forms of 'biases' in studies, some extreme, are known ( https://en.wikipedia.org/wiki/Secrets_of_the_Tribe ).

A fundamental question is to me "is someone born in a random tribe more free than we are to chose his lifepath?"

The excerpt you quoted comes from Diamond's "Guns, Germs and Steel..." book. This author opinion is quite different from some "tribal life is too violent, we are more happy" motto ( https://www.theguardian.com/science/2013/jan/06/jared-diamon... )

This is trivially true, insofar as Europeans traveled to the Americas and brought diseases, notably smallpox, with them.

It isn't meaningfully true, however. Smallpox tore through all of North America well before settlers were west of the Appalachians.

It's about the extent. Smallpox was devastating only when people traveled quickly far away. Our current COVID-19 pandemics is only possible to such an extent for the very same reasons.