Cart before the horse...
Assume that life on earth is an accident,
and therefore it MUST have happened elsewhere as well.
Just curious, though, how exactly, in your mind, does “finding a planet in the habitable zone around a distant star” support the idea that all life on THIS planet has a single common ancestry?
Regarding This planet ...
From "Darwin's Ghost" by Steve Jones, page 284.
"About a thousand genes are shared by every organism, however simple or complicated."