[spacemark]

Right, but life down there didn't independently spark from raw organic molecules. Or, rather, there is no evidence for that, whereas there is quite a bit of evidence to suggest all such life on earth is migratory to new ecosystems and shares one common ancestor.

That leap from organic molecules to "life" is still a bit of a mystery. And how often it occurs is still up for debate.

Look at Earth's history - trees existed for 60 million years before some chance bacterial mutation stumbled on efficiently breaking down lignin. And then boom, trees everywhere - every continent on earth - immediately (in geologic timescales) were decomposed.

The fact that it took 60 million years for extant bacteria to allow for that should give pause to any sweeping statements about the certainty of life and especially complex life.