Are high-level UML-style component diagrams helpful to non-technical people? How likely would they be to understand something like that and, if so, how interesting/useful is that likely to be for their understanding?
I think basic flow charts would work best here. If they are non-technical, they won't care what shapes or symbols you choose or be able to understand anything more than a general overview of the process. Anything related to UML would not be useful to them.
UML diagrams are very technical in nature. They have been distilled from informal diagramming techniques such as flow charts and structure charts (neither of which is a UML diagram!) The purpose of a UML diagram is to capture requirements and operations in a precise and unambiguous way, which necessitates user-unfriendly technical terminology. I would surely avoid any pure UML in a non-technical presentation, with an exception perhaps of deployment diagrams - and even those could be diluted to look less technical.