Teenager is a modern word describing a type of person from the dawn of history.
Manuela Blayne is a new novella told by an eleven-year-old Caucasian girl about her impressions of her thirteen-year-old African American friend. The time is old, 1910, and yet the problems described are timeless--both old and modern. The narrator Trudy Cameron takes an intense look with her teenaged eyes at the legacy of hate in her world.
Although teenagers weren't called by that name back then, they thought and acted as teenagers do today in some ways.
Have you ever googled the word teenager?
Here's what I found in Dictionary.com:
Word Origin and History for teenager
n. also teen ager, teen-ager ; derived noun from teenage (q.v.), 1922. The earlier word for this was teener, attested in American English from 1894,and teen had been used as a noun to mean "teen-aged person" in 1818,though this was not common before 20c.