There may be life on other planets. But mankind, arguably, is far different than other life forms. Laying aside all the moral and spiritual issues, mankind is different if for no other reason then we feel we’re the “caretakers” of this planet. No other life form feels this type of responsibility. This, btw, happens to be the exact purpose God gave mankind in Genesis.
It is reasonable to assume there may be life on other planets. We may perhaps find an amoeba floating around in a pool of water, but no one will ever find life as unique as mankind.
I don't believe we humans are all that unique in the grand panoply of the universe. In our own solar system, yes. Yes we are the one and only species of our kind. I don't believe we'll find other intelligent life next door. At least not indigenous intelligent life.
However, we mustn't allow ourselves to become so insular in our thinking, or so arrogant in our own exalted view of ourselves, that we fail to use our God given powers of observation and reason, concerning the question of life elsewhere in the universe.
Consider the incomprehensible vastness of just our own galaxy. It's 100,000 light years across, and contains about two billion stars. Through direct observation, we've now discovered that planetary systems around stars are the norm, not the exception - which means there may be 20 to 100 billion planets in the Milky Way galaxy alone.
The percentage of those planets which are earthlike is probably small, but even if it's only 1%, we're talking a possible 20,000 to 100,000 worlds that look just like home, and which are capable of supporting life as we know it - including intelligent life like us.
And we're only talking about our home galaxy. Extrapolate the probabilities across the known number of galaxies in the visible universe, and the sheer scale of the numbers argue for a virtual certainty that intelligent life exists in great profusion all across the cosmos.