How do I describe the feeling that the world is perfect for us to live in?
The argument, or feeling, you're describing is the anthropic principle, in particular, the weak anthropic principle
conditions that are observed in the universe must allow the observer to exist
The wikipedia page goes into more detail about this. Basically, if we're able to observe the universe at all, then the conditions in the universe must have been such as to allow us to make the observation.