Actually there's something called the "habitable zone". It's a zone that every star has, and in it, provided water on the object (let's call it X object for the sake of comfort), the conditions (temperature from the star radiation, etc.) will be just perfect for life on X to start.
I believe that we cannot be the only planet in the Universe that has life, because there is a billion billion galaxy in the Universe, each containing a hundred million billion stars with hundred million billion habitable zones and a gazillion objects in the habitable zone; who are we to say that none of them contain water AND life?
Earth is not the only planet that has life. there are other planets that people have discovered that is the right distance from their star and has oxygen. earth is the only planet that has been proved to have life. the others can hold life we just cant prove they actually have life. Some planets like Pluto have ice and water, their just to far from the sun to have life. some planets have oxygen in their atmosphere but their too close to their sun to provide life. Earth has just the right amount of everything we need so life formed here naturally. The universe is so large we can't see most of it, but what we can see doesn't have life even if they have the right conditions (as far as we can prove)
