correct me if I'm wrong: awhile ago i read some pretty interesting Texas history about the Comanches and Kiowas taking enslaved kids from Spainish Presidios and later Anglo plantations to adopt them bc while they had war bondage, the idea of enslaving children was seen as cowardly

I don't know if that's exactly how I would explain it. Culturally we don't see citizenship or family as a question of blood, but rather of allegiance. We took captives to ransom but people who could be incorporated and assimilated into our family & Nation were the most treasured.