fem. proper name, Scandinavian or German, from Ing, Germanic god-name (Old Norse Yngvi, Old English Ingwine), apparently an earlier name of Freyr. He was associated with prosperity, virility, and fertility. Second element in the name is either friðr "fair, beautiful" or rida "to ride." As a given name for girls in the U.S., almost unknown before 1940 (about the time Swedish actress Ingrid Bergman rose to fame in Hollywood); it was most popular in 1960s and early '70s but never common.
<a href="https://www.etymonline.com/word/Inga">Etymology of Inga by etymonline</a>
Harper, D. (n.d.). Etymology of Inga. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/Inga