How does the conflict with the tree, show Billy’s maturity, in Where the Red Fern Grows?

Billy is exhausted from chopping. His muscles ache and as he is just about ready to give up, he hears Grandpa coming in his buggy. Grandpa tells Billy that he needs to eat and rest if he is going to chop down that tree. Billy says he cannot leave the tree or else the coon will get out. Billy shows a maturity and determination that is rare for boys of his age.