Would life on other planets make humanity less special? Or would it contribute to our sense of meaning?

Insofar as "special" means "unique," the abundant life forms with which we share this planet make us a good deal less than "special."

In this vast universe, it is inconceivable that life doesn't exist on many other planets, and insofar as life strives to evolve from simple to complex forms, it is also pretty inconceivable that intelligent life doesn't exist on many other planets.

To argue that this diminishes humanity is the same as arguing that Copernicus's discovery that the universe was not earth-centric diminishes humanity. If you think it did, it did.

When life is discovered elsewhere, those who credit God with their existence will credit God with that as well. Those who don't will nevertheless thrill to the richness of the universe and celebrate the most exciting discovery of all time.

As DGC* said, the discovery of other sentient life would definitely make human kind less “special” if defined as “unique” in the universe. But so what? Even if we find that life is not as rare as we think, that doesn’t mean we all suddenly become moral nihilists, and go on suicidal killing sprees. This discovery would certainly add a rich and exciting piece to the history of humankind and to our understanding of the universe. Imagine the insights we could gain about our own species and the universe if we could engage in cross-cultural/planet exchange. Would these strange beings have physical forms? Would they have mathematics? How would they communicate? Could they understand our languages or our science? What kind of universals is really out there?

The possibilities that this discovery in the future could bring is the single most important factor that makes me want to live another 2 billion years, or travel into the future. And while we’re on this wish list, a winning lottery ticket and mind-reading abilities wouldn’t hurt either.

*btw-- DGC who are you?