"Poverty is declining: "
Poverty is only a metric created post-private ownership.
For millennia people had a high quality of life living off the land and meeting their needs fully outside the economic system (i'm using Africa as an example as it is one still taking place today as the Americas would be my favoured example its more in history).
Today, they are being forced into this 'private ownership paradigm' and now are considered "in poverty" the fact that our economic system is able to alleviate small amounts of problems it created is not a benefit of that system when compared with others.
However, 'poverty' or not the quality of life went down for people who made $0 to when they made $3. Our economic system would look at this $3 gain as a benefit "poverty is declining" we proclaim. But, quality of life is also declining. So, what is the real value to be measuring here. Economic benefit (mostly to the wealthy) or an increase in quality of life for all.
The measure of poverty is a self-serving metric of a flawed system.
"Also, when it comes to environmental issues private ownership of natural resources is beneficial."
Again, everything stated there is within the old paradigm of thinking. Within the context of this cultures economic and political systems... This data would only be relevant if it compared viable alternatives as comparison.
Also, in case you missed it, I actually had written a short blog on private ownership and the environment...
Is Capitalism Responsible For Environmental Destruction? A short thought exercise!
Destroying our natural world only happens because there is value to be made doing so. Which only is possible in the context of private ownership.
It will probably not come as a surprise that I think your analysis is deeply mistaken. This is a highly romanticised image of early human societies. There were some benefits with the hunter-gatherer life style, like their political egalitarianism, but that they enjoyed a high quality of life is a myth.