To anyone assuming that this is a Gary Stu story:
The great thing about this story is because the characters are living in it. They feel like people, not plot devices. This random encounter with Orsted? It'll be explained later. Just remember that he's just a person and the world is a lot bigger than he is. He's not like Ainz that is basically a god walking among mortals though you can tell that he's several heads above most people living in this world. Remember: his goal for this life is have it be fulfilling and not to rule others or be the strongest person there is. In his situation, as a child, what can you even do?
It's also important to know that whatever actions he take should be taken in comparison to the age of his body. While it's true that he does have the memories of his past life, his life experiences are pretty nil. Also, almost all capabilities he has IS because of the body he has. His mana, strength (and weaknesses), as well as intelligence. As an example, in his previous life, although he's above average in terms of intelligence he won't be mastering any new languages any time soon while as Rudeus he easily became fluent in speaking 3 more while mostly only going by the books. He also attributed every intelligence feat he had to the body he has now.