If you romanticize them you are not doing them any good. You simply cannot understand what being in their position is like. Any slight inconvenient to a modern society is a very serious event for them, eg. disease, drought, famine, etc. while you have most conveniences in life and most problems solved.
As I said in a previous comment, if you consider yourself a Marxist or a leftist you really aren't. Societies do advance, humanity goes forward. Going back 200-1000 years is not progress and it surely isn't any good. Stagnating isn't either.
Practically every research study on happiness associates it with health, family, culture, friends, purpose, religion. Comfort, physical goods, wealth are always at the bottom.
Living in simple conditions doesn't mean forfeiting health or basic sanitation. The question is still valid: you have a home, clean water, a surplus of food, friends, family, sanitary conditions, access to healthcare; but no TV, Netflix, car, laptop. You'll never afford even a mobile phone. Are you poor?
If not having internet, a phone or computer has a detrimental impact on your quality of life - which it most likely does for the vast majority of people who live in the city, have a normal job and bills to pay - then the answer is yes. If you go homeless, hungry or sick because of not having one of these things, yes. But what if it doesn't? It's not as black and white as you imply. This is much more of a philosophical question than socioeconomics (or marxism).
I never mentioned modern day commodities or technologies, you are arguing against things I've never said, and are completely omitting my main points.
According to your own arguments and words, do "tribes living off-grid" have "a home, clean water, a surplus of food, friends, family, sanitary conditions, access to healthcare"? It seems like you're completely changing what you're saying on the go.
I'll just say this: that's precisely your error, it is not a philosophical question, it is a material one. It is not ideas we're talking about, it's people and their living conditions.
Modern examples of tribal living are after the vast majority of fertile lands have been colonized by "civilization".
Imagine judging the wealth of a place like America by its Indian reservations.
Anthropologists have gone to great lengths to study tribes that have had little to no interaction with the outside world so our understanding of their quality of life isn't as biased as you'd think.
It is an open-and-shut case. If people are given a choice, it would be a good day when 1 in 100 would choose to live a life in absolute poverty. If these hypothetical secluded tribes had a choice, they would say the equivalent of "wow, antibiotics! Reliable food! Houses! Sign me up for this please, I want to be a part of it! This will make my life better!" in their local language.
And people who voluntarily do that? Vanishingly rare.