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.