Conjecture: Is it possible that the word for person in Japanese “jin” came originally from the West Asian cognate for soul, “jinn”?
Soul: every person is assigned one’s own special jinn / jinni
The word or concept of jinn as such does not occur in the original Hebrew text of the Bible, but the Arabic word jinn is often used in several old Arabic translations. According to “What are Jinn or Spirits?”, jinn are a class of spirits different from man and created before man. Jinn are created from fire and air, while mankind is created from earth and water. There are twelve clans or tribes of jann and many different types of jinn. In several verses in those Arabic translations, the words jinn (جن), jann (الجان al-jānn), majnoon (مجنون Majnūn), and Iblīs (إبلیس) are mentioned as translations of “familiar spirit” or אוב (Job) for jann and “the devil” or δαιμόνιον (daimónion) for Iblīs.
According to traditions, the jinn stood behind the learned humans in Solomon’s court, who in turn, sat behind the prophets. The jinn remained in the service of Solomon, who had placed them in bondage, and had ordered them to perform a number of tasks.
“And before Solomon were marshalled his hosts,- of jinn and men and birds, and they were all kept in order and ranks.” (Quran 27:17)
To the Jains, however, jins are humans.
“In ancient times Jainism was known by many names such as the Saman tradition, the religion of Nirgantha, or the religion of Jin. Jin is one, who has conquered the inner enemies of worldly passions such as desire, hatred, anger, ego, deceit and greed by personal effort. By definition, a Jin is a human being, like one of us and not a supernatural immortal nor an incarnation of an almighty God. Jins are popularly viewed as Gods in Jainism. There are an infinite number of Jins existed in the past. All human beings have the potential to become a Jin.” — The Jain evolutionary theory
It is possible to conceive that the concept of jin might have come from one of the early Japanese in-migrating tribes, with a concept of jin, similar to that of the proto-Jains. And that Wa-jin was a name given them, due to this observable cultural belief.