It sounds as if you do not realize how Loadrunner works.
In traditional protocols such as web/http you actually run a small C program - your script - as opposed to TruClient scripts where you run an actual web browser. These programs can be executed as threads or as processes.
Running the vusers as threads generally is more effective although there are protocols where the vusers must be run as processes.
Users' web browsers are multi-threaded processes, but that's really beside the point from a Loadrunner perspective as we only aim to emulate the traffic these browsers generate.