Although Earth was created around 4.5 billion years ago, life began to exist not long after. Due to the huge timescales involved, there is inconclusive evidence for exact dates, but nonetheless, the eagerness of life to exist was apparent from the beginning.
Our Solar System was still young, and the Sun was still cooling down after its creation billions of years beforehand. The unique circumstances of our Solar System and our planet gave rise to life. This was due to a number of characteristics that are exhibited by our ecosphere, the area of a planet capable of sustaining life.
Venus, one of our planetary neighbours, is closer to the sun, with the planet exhibiting characteristics that would not be able to support life. On the other hand, Mars is further away from the Sun, and too cold to naturally support life. However, with manipulation by man, via terraforming, Mars could indeed support life in its present state.
However, Earth, for billions of years, has possessed all the materials and suitable conditions for supporting life.
All living things possess the element carbon within them. In light of this, Earth had to have rich supply of carbon to support a rich diversity of life. This carbon was made available by the volatile nature of the Earth in the beginning, where volcanoes spewed various elements into the Earth's atmosphere.
While other elements were present, various chemical reactions began to take place which would result in the creation of new co