It's clear they know the outside world exists. They have chosen not to engage. (To put it mildly.)
As an aside, there are more than 100 'uncontacted' tribes in the world. All of them know of the outside world; all have chosen -- for now -- not to interact directly with mainstream society.
How much do they really know, though? Do they know that some of their diseases could be cured, for example?
What is striking is how many of their friends and relatives died of outsiders' disease after making contact, and how fondly they spoke of their life before. When I spoke to them, some were considering leaving the village where they now live and returning to a life in the forest.
With regards to healthcare -- the health services offered to settled tribal and indigenous people in many places is poor to nonexistent. Amazonian tribal peoples have dozens to hundreds of medicinal plants, many of which have been proven to have active pharmacological properties. Some are now used in Western medicine.
Sadly, the results simply got ignored. The woman in the book was sent by a US pharmy company and brought back many plants and samples which she had won from the tribes in hard work (they don't just tell anyone). They probably still have them in a freezer somewhere.
An experienced person I talked to said that it probably was too much trouble and costs to clear it for drugs since there often are side effects, often psychological. He took one or two of the jungle things and said it was intense. Still, it's a great loss for our civilisation that it played out like this so far.
So, we'd have much to give, but also much to gain. Our diseases could be cured too.
Net, it's very costly and it's been tried before, as far as I know, on several plants from the Amazon area. I need to find the source again, but from what I remember most plants failed against placebo. There's probably a lot of placebo effect in the efficacy claimed by people living in these areas.