You can see below the information for the simple machine, then you will know how important these simple machines are.
One of the simple machines, it has a smooth surface so that an object can be raised with less effort than being lifted. If there is no incline plane, maybe we need to us our hand to carry heavy things.
Example of incline plane: slide, mountain, and etc.
One of a simple machine, a screw is a small metal thing for holding pieces of soft things together. You can turn it to move it in or out of the things. If there is no screw, we can't hold wood or something else together.
Where I can find screw? Here is some examples: key rings, light bulbs, and etc.
This one of a simple machines,a wedge can be a very sharp things, so you can cut things. If there is no wedge, maybe we can't even cut a paper.
Example of wedge: knifes, axes, cutter, nails, and etc.
A kind of simple machines A wheel is a circle thing on a car, train, bus, and other machines that move. If there is no wheel with circle, maybe when we ride our car it will be very bumpy, so we can't sleep.
Example of wheels: car, wagon, and etc.
A kind of simple machine, which can raise or move a thing. If you want to let it work, you one thing at one ends by pushing down on the other. If there is no lever, maybe there will be no seesaw
Example of lever: hammer, clock hand, and etc.
A simple machine consists of wheel, rope, and others that can change the direction of the pull and lift a heavy things easily. If there is no pulley, maybe we can't lift things up to.
Example of pulley: flag poles, and etc.
Gears are a mechanical part with cut teeth shape to fit with teeth on another part, so as receive force and motion. If there is no gears, maybe there will surely no machines, like clock, computer, and etc.
Example of gears: watches, clock, and etc.