FF6 had Relm and Gau, ff9 had vivi and eiko, 12 had vaan, penello, larsa, half of the party in 13 were underage ... then there is the older teens like rikku, yuffi, zidane, garnet, ramza...
I'm not advocating for children as playable characters just pointing out how the series has no problems throwing child protagonists on the frontlines... as for children as leaders or fighting in wars look back at some of the child emperors and kings, look at Viking children who would start raiding as soon as their balls dropped... again not advocating...
