Isn't it a highly competitive all-terrain sport?

Surely it's an activity for people who enjoy tackling challenges set by a course planner?

Isn't it an event for families?

 Actually - all of the above! Even top-level events have courses suitable for all ages and abilities in addition to those for elite athletes. You can watch British Orienteering's introductory video here - or, at the other end of the scale, follow the GB athletes