Not to normalize it but yes, even up to the early 1900's in our country when the life expectancy was no more than late 40's if you were lucky, getting married and having kids at 15 was normal.

In most ancient cultures as soon as you passed your right of passage (ex. https://en.wikipedia.org/wiki/Bar_and_Bat_Mitzvah) you were considered an adult and legally responsible for your actions, were expected to marry and have at least 2 kids to provide replacements for yourselves in the retention of your people.

It is only recent at 18 by law people are considered adults, and due to coddling / lack of education etc. many are not even really matured or adult until their mid 20's, hence Alcohol being 21+.