Well. Computers are created in the image of human beings. What I mean by this is, computers are exact replica of humans in terms of features. We are all aware that human beings take the input wither by seeing or by hearing; therefore eyes and ears are acting as Input Unit. Similarly, a computer has to take inputs through its input units which are normally Keyboard and Mouse. Therefore Keyboard and Mouse can be co-related to Eyes and Ears
Once we take the input we process to generate the result. The processing/execution happens in the brain. Similarly in the computer, the processing happens inside a device called as CPU ( Central Processing Unit ). Therefore CPU can be co-related to Brain.
Once processing is done, humans can give the result either by speaking or by writing. So, Mouth and Hand can be considered as output units. Similarly in the computer, the result can be displayed on Monitor and printed using a printer. Therefore Monitors and Printers can be co-related to Mouth and Hand.
In the case of humans, the data is stored in the brain and on the computer it is memory.
The parts of the human body are connected through Nerve Systems. In computers, all the devices ( Input device, Output device, Processing device and Memory device ) are connected using wires. The wires are technically called as Bus.
Finally, if a human is to be called alive then there should be Soul in him. Similarly in a computer, if it has to function, Operating System a.k.a OS should be there. Therefore OS is the soul of the computer.
It is the OS which brings the computer to life.