Look around you. Are people on the ground, or are they floating around?
The force of gravity keep a bycicle on the ground.
Yes, it is about 1/3 that on Earth.
Gravity
enough to keep us on it
The force to keep us and nearly everything else on the ground is GRAVITY.
It will keep on flying and never come to ground
The upward normal force from the ground pushes against gravity to keep you from sinking into solid ground when you stand. The normal force is caused by the atoms in the ground that resist being compressed by your weight, resulting in a balanced force keeping you upright.
it helps it stay on the ground instead of falling or floating
Yes there are enough gravitational forces to keep the satellites orbiting earth.
Mainly because Earth has a large enough mass, and therefore a large enough gravity, to keep an atmosphere.
Earths gravity isn't strong enough to pull it into the Earth, however it is strong enough to keep it from drifting away.
because all the gravity is not strong enough to keep the gasses in together