Built on someone's name. The surname says not what he did but whose he was.
A surname from a given name answers not what he did but whose he was. It is the oldest form: first it named children, then it settled on the line.
The meaning here is doubled. There is the meaning of the ancestor's name — and there is the fact that someone once chose it. The surname preserves not an occupation but a choice made generations before you.
That is why these resist literal reading most: between today's bearer and the meaning of the root stands a living person we know nothing about.
76 surnames taken apart.