Why is gravity so important to life? explain.

Let's pretend gravity didn't exist.

We'd still be living in the Stone Age because Einstein would have floated into space and a vast majority of us would just be hanging on to rocks and trees, trying to survive.

Also, gravity keeps our planet orbiting the sun...
or else we'd be actually all dead.

Erase all I said earlier.
A whole majority, ahem, everyone, would be gone if gravity didn't exist.

It also causes ocean tides.

In the area that she observed, the water level fell 13.64mm over 6.4 years, for an average annual rate of change of:
-13.64 ÷ 6.2 = -2.2 mm/ year. 

The difference between how much average water levels rose and how much water levels in her part of the river fell is:
1.8 -(-2.2) = 4 mm/year

During the 6.2 year period: 
4 mm/year * 6.2 = 24.8 mm