We look at things in terms of our lifespans. What if you could take a step back and expand out 100 years at a time. This little bits and pieces of information will eventually present a full picture. What happens is that when the full picture is developed this earths humans will be prepared. Basically give bits and pieces over time.
Just imagine telling an entity look you for some reason assumed you were the only ones even though you clearly were left proof of other life forms in fact many have presented themselves to you but you said the people who saw them were crazy.
Basically they are proving bread crumbs to the public until eventually folks will be expecting it. It’s not about the top percentages it’s about culling the masses.
Now my what it is this. What if a lot of the things we assume were sci-fi (angels, devils, aliens, etc) were just aliens. Even though I didn’t like it I think that movie Jupiter Ascendings world is closer to reality.