Of the 8,000,000,000 people on Earth, there's maybe 12 who could dream up a functioning intrastellar space program. Once that was in place, we'd need another dreamer who understood every part of it to wypipomagik a way to travel between stars.
It's entirely possible that other planets out there could contain life. Maybe even highly organized and proficient, like the Chinese. But if they killed off all of their Germans, then they'll never leave their planet's surface, much less travel to ours.
"Mankind" did not travel to the Moon. Germanics did. That's how rare True Ability actually is. No one else on Earth, given another 10,000 years, would have thought it up.
The aliens, if they exist, are just practicing the best way to make dinner recipes, not colonize the cosmos.
