Storytelling has been around since humans have. Humans have a natural inkling to tell stories and to document the things that have been done. We are able to distinguish history from carvings on cave walls and etchings in stone and recreate these stories from the past. Even though what we think of as the classic story format is written word, visuals are easier to process. If you look at the history of visuals then compare it with the history of written word you see a difference in how the two originated. That difference in and of itself is a good example of how visuals can be easier to distinguish than written language.
Written language took time to establish and in many cases was started only after drawing became inconvenient. Written word has to be taught and takes time to master. In contrast, visuals, with one glance we can glean the emotions expressed, the people involved, where the story takes place, if there are any problems, what the people look like and tons of other things that would take lots of time to describe in words. Visuals are also accessible to anyone from any background. To interpret visuals you don’t have to be a master at a language and you can still have an idea of how to interpret the story that is happening.
The ability to read visuals and to create a story from looking at a picture is something that comes innate. When you think through things, you typically don’t think in written language but rather in pictures. By using visuals as a convenient way to tell stories, you control exactly what people are seeing and how they are reacting to your story. Other mediums don’t have this advantage and because of this visuals are an easy way to tell stories and reach a broad realm of people.