You say the doctors would treat (previously unknown diseases) at a discount price. Unless the first contact with the outside world is a CDC team in full biological isolation suits the chances are good no villager would survive long enough for a doctor to come. But lets set that aside for now.
And how are the villagers going to pay for treatment, even at the discount price you mention? The village probably has no idea of money. Are you going to build a school to teach the western concept of "money" before treating the diseases killing the village? Or are the doctors going to accept barter goods? If so what would be acceptable? Gems? Wood? Animal skin?
Ok Say contact is made, then what? They don't have the knowledge to even integrate into any "civilized" society. Should we make them dependt on forms of welfare? The adults will never be able to learn how to exist in modern society. Should we just kill all the adults and put the children in "schools" to learn how to exist in our society, robbing them of their cultural identity? It's not that far fetched, look how Americans treated American Indians.
As to your first question, "Is it all relative" I would say "yes" to a certian extent. You mentioned things like rape and child abuse that you say are examples of actions that every culture holds as "bad." However not ever society views these actions as evil. I can not think of a single act that is viewed as "evil" or "wrong" in every society. Even cannibalism and incest are accepted in some cultures. Are you going to tell these societies they are "bad?"
In order for one culture or society to be "bad" or "good" there must be some Supreme Moral/Ethical Judge. For many people they view morality and ethics through the lens of religion. But again you come back to the issue of which religion (or other moral/ethical system) has the final authority of "goodness."
From your post it sounds if you have set yourself up as judge of all cultures. I missed the ballot where you were elected, because I'd have put myself on that ballot.
You call the village a hellhole because they don't have modern amenities, but if i remember from my anthoropoly course, most hunter gatherer societies only work approx 10 hours out of the week to secure food. Most people in a "civilazied" have to work 40-60 hours per work to earn enough money to support their family. Additionally many hunter gathers are egalitarian, which can be argued to be the most fair way to distribute wealth.
You mention medicine and disease they can't heal. We suffer those in the most advanced societies in the world. The level of treatment you receive is entirely dependent on you level of wealth. Unless you believe that a street bum receives the same level of care as say Bill Gates (one of the richest men in the world). But what about the average person? They only receive treatment up the level of their health-care plan. With meany diseases this only prolongs the inevitable. I remember a study that concludes that many "primitive" societies do not suffer the same diseases that "modern" cultures do. Their diet is entirely organic, and they don't come into contact with the contaminates that we do. I acknowledge that are some conditions that we could probably treat better than could. But does the harm of "contact" out weigh the few positives we could bring?
And we circle back to the position of who gets to decide that? So yes it is relative.