Changes in Huck Fin beyond Chapter 16

In Huckleberry Finn, between Chapter 16 and beyond there are several differences taht can be seen. Since Mark Twain put the book down for 3 years, i guess he wasn't be too cautious about his characters. AFter chapter 16, it seems that the language that Huck uses is more 'proper English'. It seems that Twain thought that Huck would also be three years older, cause the way that he speaks shows taht he has learned more English compared to what he was speaking before chapter 17. Also after chapter 16, Huck starts giving more details about events. THe way that he describes things is much more detailed compared to what he used to do before chapter16. Huck is more observant and thus gives more details. So i feel as if Twain thought taht Huck has grown older, since it was 3 years that he put the book down. Becuase if you think about it, we find out in chapter 17, that Huck is Buck's age, around 13. So three years ago, huck would have only been 10 and there is a significant difference in maturity between a 10 year old and a 13 year old. This goes along with his use of more proper English because not only is he giving more details about his adventure, but also talking in a style that we would understnad better. Also after chapter 16, i feel as if the novel isn't 'the adventures of huckleberry finn' anymore. It seems there is much more involvement between other characters in the novel and not just solely focusing on Huck. For example, Twain includes the Shepardson family and the Granderfords, and the Duke and King as well. WHile reading chapter 25, i felt as if Huck had nothing to do with it, since he was just standing there and telling us what was happeneing. Where as before 16, he was doing all the action himself.