There are lots of unexplained natural phenomenon out there.
A sure landing by ETs would change many things but not all things. Assuming they weren’t here to harvest us we would mostly go on with our lives. After a few months the novelty would wear off and others in the universe would simply become a known fact.
Surely the senate would pass an immediate bill to protect the aliens from us terrestrials so they could sue us in our courts in case we reported them to proper authorities.