They have basic survival knowledge

The people of these tribes have a deep understanding of their natural world through botanical and zoological wisdom and offer unique solutions for sustainable living. A lot of progress compared to the history of human development. They know how to hunt, set up tents and have self-defense weapons. Many of the drugs used in Western medicine are derived from tribal people and have saved millions of lives. The tribes that have not been contacted likely hold the key to many other secrets in their forest.

If we don't talk about the factor of living a long and healthy life, it is quite understandable that the tribes still exist. They meet the daily needs of eating and breathing. And they also have the ability to reproduce like everyone else. Life is met with basic needs, so it goes on, day in and day out. One positive thing, if they don't know the complicated and polluted world outside, it can be even more pleasant. Equal communities, without strong class divisions or distinctions between rich and poor. The emergence of civilized humanity maybe upset and change their normal rhythm of life.