If you stick a metal screw on a magnet it will stay there. You can roll it around with your finger but it will stay unless you really yank it off. Think of our planet, Earth, as a big magnet. It is so strong that it holds us on the ground very easily even though it is round like a ball. It's not at all like a magnet.
Gravity also makes it hard to climb a rope or a tree.
It kind of pulls you back down and makes you tired. It also makes it hard to pedal up hills. But the great thing about gravity is it makes going down hills really fun . It pulls you down the hill until you're going fast. It's a good thing we have gravity .