I admire the human drive to solve the cosmic puzzle, find something bigger and more meaningful than us, but so far it looks like there is only one place in the Universe that has life. And even planets with relatively favourable conditions like Mars are dry, lifeless husks devoid of any, even the simplest lifeforms.
Two scenarios (at least):
1. God exists and specifically seeded life on Earth.
Even if this is the case there is still no reason meteorites couldn't carry microbes from Earth to Mars. It doesn't seem like God cares about quarantining life to earth, seeing as we made it to the moon.
Also, why bother making a universe so mindbogglingly huge and vast only to put life on a single planet? Makes more sense for God to seed countless planets out there with life. And indeed there are a few verses in the Bible that imply Earth is not God's only creation.
2. God does not exist and life emerged naturally.
If this is the case then that means life can emerge naturally somewhere else with identical conditions, and given the number of stars/planets/time elapsed, this seems like it could be a high probability (hard to know, though, without understanding exactly how life emerges).
Secondly, it remains a challenge to categorize and define the envelope for what is and isn't "life". We have a decent hold on "earth-like life" but it will not be sufficient for all that might be encountered in due time (or already exists unbeknownst to us). If you have ever defined an ontology you know that it becomes more and more challenging to put definitions to the universals as you climb up the ontology. At the top, the universal from which all other universals inherit is very commonly left descriptionless.
Last, there are many alternative to the Christian One-God view that you express (I am sure you are aware and chose to limit your points for brevity). There are spiritual books that explain/propose/posit the universal disconnect between the living conscious beings of Earth in this material plane and the myriad of "beings" that exist in other higher dimensions/levels/shells.