Water is the essential source of life in our universe.
... universe include other solar system too and we still don't know whether there can be living beings who could survive without water. I guess you meant the "world" we live in.
Water is essential for the existence of all living beings in our planet.All living creatures including human beings, plants and animals are impossible to live without water.
When you say all living creatures, it refers to everybody and therefore this specification, (plant, animals, human beings) sounds a bit redundant.
This colorless, flavorless liquid is the natural gift giving to all the living things in the earth.
... first part is fine because you are telling the reader something that you haven't told before. But the latter part is a repetition of the same idea you've been telling in first few sentence. Repetition, be it the words or ideas, makes the reader bored.