In what ways is Luster a stereotype, and what do we understand about Luster because of this in "Split Cherry Tree"?

In the beginning of the story, Luster Sexton seems to typify the backwoods country bumpkin with very little education and knowledge of the world other than his immediate environment.

When Dave comes home late from school and informs his father of the reason, Luster immediately becomes defensive of his family and their socio-economic situation, a typical reaction for people with little education and money. He also criticizes Professor Herbert for being an outsider:  

"Poor man's...

In the beginning of the story, Luster Sexton seems to typify the backwoods country bumpkin with very little education and knowledge of the world other than his immediate environment.

When Dave comes home late from school and informs his father of the reason, Luster immediately becomes defensive of his family and their socio-economic situation, a typical reaction for people with little education and money. He also criticizes Professor Herbert for being an outsider:  

"Poor man's son, huh,....I'll attend to that myself in th' mornin'. I'll take keer o' 'im. He ain't from this county nohow...."

In the morning Luster, carrying his .44 in a holster, accompanies Dave to school. There he appears too large and clearly out of place. Nevertheless, Luster Sexton is willing to listen and learn, unlike the stereotypical Kentucky backwoodsman. Further, he exhibits a knowledge and respect for nature that exceeds that of Professor Herbert, as, for instance, he explains how black snakes serve farmers by killing crop-damaging rodents, so they should not be killed. And, although he is from the backwoods, Luster is not unwilling to learn. So, when Professor Herbert shows him germs under a microscope, Mr. Sexton is not so ignorant that he refuses to understand what he sees. Instead, he acknowledges that learning has changed since he attended school, and Dave must go further in his education so that their family will not become close-minded and remain backward.

"School has changed from my day and time. I'm a dead leaf, Dave. I'm behind. I don't belong here....
You must go on to school. I'm behind Dave. I'm a little man...."

By the story's end, Pa has demonstrated that he is no longer stereotypical, but is many-sided and has displayed the capacity to learn and change.