Many captive girls, especially if older than ten or so chose to remain with the Indians because they knew they would be ostracized if they went back among the white people. Read about Cynthia Ann Parker and the Comanches. There were several more such, especially in the 1700s farther east. Young girls and sometimes young boys were often taken specifically as adoptees because some tribes had a less than replacement birthrate and supplemented their population with young captives who became assimilated. Some captive boys grew up to be war chiefs in America and the West and in Canada.
It was/is a very common part of tribal warfare. Even the Russians are accused of it in Ukraine.
It has been a part of warfare for a very long time, longer than recorded history, for certain.
It may have been because nobody knew about Stockholm syndrome then.
This Mary Jemison married a chief, I believe. Throughout the decades, and due to various circumstances, she became a wealthy woman and landowner.
She recalled everything so clearly about her life, and when she was older a man, a doctor, I think, interviewed her and wrote her biography.
(Me ... I can’t remember anything about my life.)