Her’enu lahem et ha-avoda shelanu.
Would it be correct to say, "הראינו אותם," in place of of "להם"?
No, "הראינו אותם" would mean "we showed them" (as in actually showing them to other people and not showing them something).
Good point. We showed them to other people:
הראינו אותם לאנשים אחרים.
Is adding אנחנו incorrect? I get that is isn't necessary, but I don't believe it to be wrong.