Life is order, entropy is chaos

Life is order.  Entropy is chaos.

Life exists because it is more stable than random chemical elements heated by the sun.

Individual elements like oxygen and hydrogen gas (O2 and H2) tend to combine into water and release energy - under most terrestrial conditions water is more stable than the elements in their molecular forms.

Life exists because the chemistry of elements combining into molecules thermodynamically favoured a level of complexity where biological systems emerged with the property of being able to reproduce themselves.

Life uses energy to maintain order for a time, before returning it to the universe as heat.  

The more life in a system, the less heat.   While the sun shines relatively constantly on the planet, the more life there is, the more of that energy is captured and stored in biological structures, rather than simply heating the planet or bouncing back into space.  

When a drop of water falls on a hillside it is carrying the energy from the sun that allowed it to evaporate into the atmosphere before condensing into a droplet and transferring that now kinetic energy to the hillside.  It can either transfer some of that energy into biological systems, increasing order, physical systems by shaping the landscape via erosion, or release it's energy as the from friction as it rolls down the hill.