I would trace the history of animation in Japan further back. I believe its roots are in a form of street performance art called "kamishibai".
> Kamishibai (紙芝居, "paper play") is a form of Japanese street theater and storytelling that was popular during the Great Depression of the 1930s and the post-war period in Japan until the advent of television.
> Kamishibai were performed by a kamishibaiya ("kamishibai narrator") who travelled to street corners with sets of illustrated boards that they placed in a miniature stage-like device and narrated the story by changing each image.
The oldest surviving clip of Japanese animation from 1917 (which was delightful by the way, thanks for posting the link) - I think we can recognize that there's already a visual language established, the way the characters are drawn. It's crude, but there's surprising sophistication, which seems to imply a historical context of trial and error over generations.
> Kamishibai has its earliest origins in Japanese Buddhist temples, where Buddhist monks from the 8th century onward used emakimono ("picture scrolls") as pictorial aids for recounting their history of the monasteries, an early combination of picture and text to convey a story.
https://en.wikipedia.org/wiki/Kamishibai