I haven’t stopped thinking about this since the American missionary was killed by the uncontacted Sentinelese people. What if Earth is the uncontacted & protected community of the galaxy?
It seems likelier that we are too far from interstellar civilisations to be visited by them, or that there's no interstellar civilisations because of a Great Filter, or even simply that earth is not interesting enough for them to visit. Or worse, they do visit, but the human race is not interesting enough for them to make their presence known to it.
But I would imagine that an interstellar civilization that has discovered thousands of life-bearing planets would start to develop some criteria about what type of life is interesting or not. It could just be that nothing on Earth meets the criteria to be interesting.