[wolverine876]

One interpretation of the origin of such monsters, from Beowulf:

That bloodshed, for that Cain slew Abel, the Eternal Lord avenged: no joy had he of that violent deed, but God drove him for that crime far from mankind. Of him all evil broods were born, ogres and goblins and haunting shapes of hell, and the giants too, that long time warred with God - for that he gave them their reward.

The original Old English text refers to the monsters as eotenas ond ylfe ond orcneas, swylce gigantas, and other translations seem to disagree on their meaning; however, orcneas meant evil spirits, according to the Oxford English Dictionary and to Tolkien (who was a leading scholar of Old English in his day job).[0]

(I assume you are not saying that "people from other communities" are actually monsters, but referring to historical ignorance.)

[0] If you can access the OED, see the entry for orc.

[rebuilder]

I'm saying that people historically sometimes act like monsters when they meet people from other communities. Enslavement. Pillaging. Murder. Rape. Salting the fields. Etc. etc. etc.