David Brin's later works in the Uplift Universe were along that pattern. Humans were involved in a titanic multi-galaxy war, but it turns out that only the oxygen-carbon species were part of it. There were entire other civilizations along different biochemical lines, with interests in different kinds of planets, and they pretty much ignored each other.

It seemed like Brin thought of this after the first couple of books were finished, as there wasn't a good explanation for why the systems our heroes traveled through didn't have any noticeable traffic to their high-population-density gas giants or whatever.