Recently I spent time with my grandkids. I'm always fascinated to see how language develops in kids. I love hearing "Her" doesn't want any, instead of "She." Pronouns are tricky. My granddaughter is 3.5 and is still a little stumped by their use. I suppose since kids are naturally inclined to the possessive, it makes sense that it is the preferred form.
The one I really like, though is "more better." As adults we know that "more" can be used with countable objects and ideas, while "much" is generally used for the uncountable. More is also comparative, having more money than another, for instance. There are many other distinctions. A quick Google search will lead you to many tutorials for non-English speakers where the differences between "more" and "much" are outlined.
But, what if we think of "better" as something that could be countable. We say "more of a good thing," "more appropriate," "more useful," etc. Are good things, appropriateness, and useful countable? I think not. However, they are comparative. So, for a child it is perfectly reasonable to say that something is "more better." It is comparatively better than it was. Better is already more, already comparative, I guess. More than what was already good. So, how do we describe when something is even better than before? Much better.
Then we have the "much more." I have much more thinking to do on this topic.
P.S.
On the topic of language, I love this bit by British comedian Michael McIntyre about odd phrases, like hanky panky....
https://www.youtube.com/watch?v=uJEqXJRK4Q4
