I've heard some plausible arguments explaining the mind boggling good fortune Earth has had to produce intelligent life. And also the explanations of the vastness of space which make it plausible that there is "lots" of life out there which we will simply never be able to encounter due to distance.
Not just distance, but time.
How long has human civilization lasted? 10,000 years? How much longer until we go extinct? Another 10,000? If we are lucky?
20,000 years is an eyeblink to the billions of years old universe. Many intelligent civilizations could have popped up and petered out and never existed at the same time as another.