I guess I'm missing the part where the things you've identified translate into maturity. Though, to be honest, maturity is a rather abstract term. Oh wait...This is an easy one. 200+ years ago, the average household needed their kids to start working on the farm or family business as early as they were capable. Can you carry a bucket? Guess what, you're working.
Let alone the fact that the average life span was 20 years shorter, and as soon as women came into their cycle, they were marriage material. Some at 12, some later.
maturity
n. the state, fact, or period of being mature.
mature
a. fully developed physically; full-grown.