19:04:17jcowanThe earliest Unix had no concept of users, being in fact a single-user machine. The point was to provide a functional meta-language that represented stateless computation between arbitrary black boxes.
19:05:04jcowanThe black boxes could compute with effects and generally did, but no effect could spread beyond a certain scope, short of kill().
19:06:28jcowanMultics did indeed have one process per user as a rule, which is where the shell got its name; it was literally a shell that dynamically linked the code you wanted to run into itself, all programs being represented by libraries with a fixed interface.