As any being who exists on a planet covered with biology, in a solar system surrounded by other orbiting bodies almost fully covered in at least basic organic compounds, it should be self evident that life is just another facet of the physical, chemical, and geologic processes that comprise existence.
It is highly unlikely that we are alone.
That being said, the prospect of simultaneous existence is rendered pretty null and void given our very short lifespans and the vast amounts of time, space, and technological ignorance which separates us from those hypothetical neighbors.
Isolation tends toward the illusion of complete solitude.
If your next door neighbor is 100,000 years away, what does it matter?