The universe is extremely old - some 13.7 billion years. And light travels at nearly instantaneous, but finite and fixed, speed (299,792,458 meters/second in a vacuum). And thus, the observable universe is unimaginably vast. Within the observable universe, there are an estimated 2 trillion or so galaxies, comprising 200 billion trillion stars, and among these stars, say 10^25 (1 followed by 25 zeros, or 10,000,000,000,000,000,000,000,000) planets and similarly many moons.
Among these 10^25 potentially observable planets - intelligent life seems all but certain.
And this is just the observable universe. Perhaps the universe extends - as many astrophysicists believe- without end. In which case there are an infinitude of planets among which intelligent life might exist - and thus, intelligent life, however unlikely, must be infinitely present.
And our universe might not be alone. There may exist infinitely many universes in numerous plausible but theoretical ways - the quantum many-worlds hypothesis for example.
It's hubris to think that we are the lone, singular intelligent species among all the rocky outcrops, moons and planets gravitationally bound - or possibly free-roaming - to all the stars present in all the galaxies in all the universes.