How would humanity respond to the discovery of alien life?
It would certainly make the universe more interesting, but it would also make us less unique. The question is whether it would provoke in us any sense of cosmic modesty. Conversely, if all our searches for life fail, we’d know more certainly that this small planet really is the one special place, the single pale, blue dot where life has emerged. That would make what happens to it not just of global significance, but an issue of galactic importance, too.
And we are likely to be fixed to this world. We will be able to look deeper and deeper into space, but travelling to worlds beyond our solar system will be a post-human enterprise. The journey times are just too great for mortal minds and bodies. If you’re immortal, however, these distances become far less daunting. That journey will be made by robots, not us.