I'd argue that the jump from 0 to 1 of "knowledge of life on other planets" would be huge. Currently, we have an almost pseudo-religious understanding of what place life holds in the universe, but that's based on the fact that when we've looked up at the cosmos for all of history, it seemed impossibly devoid of anything familiar. The discovery of life on another planet (even if that life somehow originated on Earth), turns the proposition of finding intelligent life elsewhere from at best a 50/50 question of belief into a near certainty. And that is huge.