I don't know which definition of life you go by, but most of them seems to be pretty lenient. Not sure how you can be confident about earthlings being the only ones living up to those (pun intended).
What I see is bunch of arbitrary capabilities, that we decided sum up to being life.
"the condition that distinguishes animals and plants from inorganic matter, including the capacity for growth, reproduction, functional activity, and continual change preceding death."
Technically if we decide to INTERPET this leniently, then phenomena like crystals and fire would qualify as life. So would viruses.
Yet, it also says "the condition that distinguishes from inorganic matter", and those are not "organic matter".
And what is organic matter? Well... that happens to be defined as carbon-based DNA/RNA coded proteins. That's QUITE specific to earthlings.
If aliens turn up, everyone will be too busy worrying about aliens to care about some prediction being wrong.