Yes we do know that. There hasn't been a shred of evidence of life outside our planet.
We didn't think anything lived on the ocean floor where photosynthesis can't reach but damn there are.
Did I ever claim that? No.
Next red herring.
All humans believed that. Turns out life can happen in places we didn't think could harbor life
You keep side-stepping the issue. This isn't about places that can "support life", I have no doubt there are plenty of worlds out there that can support life.
The creation of life, and a habitable zone that can support life are two entirely different topics. Life does not spontaneously manifest itself just because there is a habitable environment. Because of that fact, there is no grounds to believe life exists out on other planets simply because there is an environment that supports life.
How do you think life manifests? I say all the ingredients for life come from the inside of stars that died. They blew up and blew chunks of all the ingredients for life into the universe and when those microbes get frozen out in space they stay dormant until they crash into a planet that can harbor life.
Life is inside comets. Plant that life seed on a planet and look at what happened on earth. You get the diversity you see here. We know how life gets started on other planets because of what happened here. We don't have all the answers but we are pretty sure god didn't poof fully grown animals into existence.
There are lots of scientific theories I'd go with before the religious story of creation.