There is a distinct trend in ergonomics of the 'lone ergonomist'. Because even though the job requires liasing with countless engineers, designers, workers and managers, you will usually do so on your own; or at most with a couple of fellow ergonomists.
Usability professionals work similarly, but are more likely to work on a team when doing laboratory work.
But whether you're alone or surrounded with colleagues, there are many routes you can take to become an ergonomist; many settings in which you will work; many roles you must play, and a variety of job titles, tools & tasks that go along with each