I think Twain got the characteristics of that age group just right.

As a teacher, I deal with students that are in the 13-14 age range.  In
some ways they act like 17-18 year olds.  Then, they turn around and act
incredibly naive, even childish. Some of the girls go to the prom with
older boys, yet still play with dolls. The boys want to be treated like
adults, yet they play with toys and will do just about anything for a piece
of candy.  Of course, to adults, it seems like they want to be adults when
we want them to remain children and when we want them to act mature, they
act like 3rd-graders. It's the nature of the beast.  And Twain understood
that.

The savvy Huck had learned to take care of himself.  The naive Huck was
still a boy.

C.J. Peiffer