Come on, if you changed "anything"--the tilt of the Earth, the speed of its rotation, the distance from the sun, etc.--the planet would've beeen completely sterile. Quite some "conincidence", I'd say...
Life is tough. That doesn't mean you and I are, but in general, life can surive all sorts of otherwise apparantly deadly environments. There's even an archeobacter that can rebuild its genome after being irradiated.
Anthropic principle. The only reason we're here to comment that earth is unusually suited for life is because earth is unusually suited for life.