Hi, hanuman2000,
This is incorrect. As you can see, important is an adjective. So you have to rewrite the sentence as "Water is important in our lives." or "Water plays an important role in our daily life."
This is a perfect sentence.
The sun rises in the east and sets in the west.
I would think that you are talking about your friend whose name is Sun. And she's a shiny girl. Usually, 'Sun' is the abbreviation for Sunday.
Hope that helps.