>there was very little need for personal mobility in society

People regularly traveled to nearby market towns. There's still a strange omission: why didn't anybody in Europe invent the Chinese-style wheelbarrow, with the single central wheel? This seems to be the closest equivalent to a cargo bike that works well without modern materials. It's well suited to moving modest quantities of goods over poor roads, unlike the European wheelbarrow which is optimized for quick loading/unloading, and best suited to moving things short distances.

Merchants, sheperds, peasants and the like travelled for sure to nearby towns to sell their goods.