NeverarGreat said:
This is a good, well reviewed book:
https://www.goodreads.com/book/show/186074.The_Name_of_the_Wind
The main character is a Gary Stu.
Discuss. Or better yet, let’s not.

I’m not going to read that book, nor is “well reviewed” a guarantee of good writing (The Force Awakens is well reviewed too), nor am I going to simply take your word for it that the main character is a Mary Sue. Given that one of the most common arguments from Rey apologists is, “If Rey was a Mary Sue then so was Luke,” it’s obvious that many people don’t know what a Mary Sue is. Luke wasn’t even close to being a Mary Sue.