(1) Remember the Principle of Mediocrity again.

(2) Well possibly the people who say the probability of life arising by chance are 1 in gazillions to the power of gazillions are actually correct. I've said this before, that although it could be extremely improbable, the probability is still greater than zero. It has a finite chance of happening. Hence the Strong Anthropic theory, which I find quite attractive. However there have been several papers debunking this idea. Anyhow, the logical position is that if it happened on Earth, and it happened quite quickly as well, that means it should be commonplace on Earth-like planets.