Modulation is a way to shape something to give it a meaning by the shape. In the old days mankind was very limited in modulating to our perspective. They had to use natural resources. They used sticks, bones and stones to create modulated objects. As the sound of speech was discovered it was modulated all the way.
From the very first yells, to modern articulated conversations man uses his vocal cords to modulate sounds, making them containing information. The early days of speech will have been difficult. By not knowing what the other party trys to make clear, it is a big job understanding each other.
Over time verbal communication grew to be the main advantage of mankind. Using stories to instruct the young ones what is custom and what is bad. Using lyrics to memorise these stories over generations, and eventually writing them down.
The stories as told are nice indeed, however they are just carriers of the message. The story is a modulated sequence of words while the exact words are of no big deal. As long as the carried message contained in the story is not altered too much the purpose is there.
Modulation has a lot of different manifestations. Often layers of modulation are topped onto eachother. Take the stories for example, vocal cords modulate air flow to make sounds. These sounds form words. The words form a story. And contained inside the story there is a message.
Does this sounds too complicated for the purpose? It is not. The modulated sounds have to carry the information from one person to the other. The words have meaning, recognised by the listener. Making a story that really could have happened. And while the included message is often very simple, the story is mostly easy to remember. Thus spanning generations and time.
Current day technology uses modulation for the same purposes. One way of modulating to enable transport another to enable storage. Jet another modulation to make the story transparent to one receiver while containing information for the other.