It seems to me that this interpretation would only make sense if all of the enemy are orcs/trolls/etc. But that's not the case at all. Tolkien draws a clear distinction between the truly evil non-human creatures and the bad/misled humans.

> odd-looking people (some in Bree, IIRC)

"The Southerner", who is later speculated to in fact be a rather human-looking orc if I remember right.