I agree. I think the more anthropomorphic (socially) the aliens are, the more it makes sense that they would go along with our own social constructs and thus make contact through governments. An alien species that’s extremely similar to humans would be expected to contact government leaders, in the same way that a group of humans would likely pursue diplomacy when contacting another group of humans. In popular fiction, we see that in stories like Men in Black or Transformers, where the aliens are apparently mostly complicit in the governments’ efforts to conceal their existence from the general public.

Of course, it would also depend on the aliens’ goals and the circumstances of their arrival on Earth. If they just want the planet, they may as well show up with guns blazing, as in War of the Worlds or Attack the Block or Battle: Los Angeles or Skyline. If they’ve landed in distress, they also likely wouldn’t bother concealing themselves, as in District 9.

Anyway, I’ve always been fascinated by imagining what would actually happen if some fairly anthropomorphic aliens really did show up tomorrow, on a diplomatic mission (not guns blazing). Portrayals in fiction are fascinating, where world religions try to explain it (or view it eschatologically), governments debate whether to preemptively attempt to annihilate them, etc. How would I react?