We can look to world history for real examples of what people do when contacting a new culture:
Religions send missionaries to teach the heathen how to pray to the right imaginary figure.
Scientists protect the new found cultures and study them for clues to understanding our own past.
There are still numerous uncontacted peoples in places like New Guinea and Brazil. If what you said were true then why aren't the biologists down there now teaching them about Darwin? The only thing keeping the missionaries away are reputations for cannibalism and headhunting as well as more enlightened governments run by people with their own history of being colonized and converted.