On top of that, a lot of (foreign) names for tribal groups or communities boil down to:
"Those Guys Who Aren't Us".
This happened for the same reason, explorers talking with a group they had contact with and asking them about their neighbours. These names are known as exonyms because they've been applied from outside the group.
One famous example is Eskimo - the etymology is disputed but the most accepted meaning is "The Guys Who Wear Snowshoes", as named by tribes who did not wear snowshoes. That's why the word has been phased out for Inuit - lit. "The People" (or, essentially "Us").
Or my favourite one - we don't know what the Celts called themselves. Celt comes from the Greek keltoi, meaning "Foreigner". The Romans referred to the Celtic peoples of modern-day France as gauls, meaning... "Foreigner". The French refer to the Welsh as gallois, meaning... "Foreigner"!
Even "Welsh" essentially means "Foreigner"! It's derived from a generic Old German word for people living in Gaul. But the Welsh call themselves Cymry, which means "fellow countrymen".
In short: scratch the surface and many names mean either "us" or "them", and no one in human history has had any imagination.
You can't complain about people being called 'The People' when you live on a planet called 'The Ground'.