here is what i believe.

If we have been visited before, then they are still here. there could be whole colonies below the ocean's surface we know nothing about. Our ocean floors are largely unexplored, and we have no way to get down there.

I believe that we are not the only planet with life in the universe.

I also believe the far side of the moon is an excellent place for others to watch us if they were so inclined.

I also believe we will not find any other life forms in this solar system beyond possibly simple micro organisms, algea, and lichen.