From what I remember from the web novel, this hero guy won't be the stereotypical fool who thinks with his own version of absolute righteousness. Sure, this kid is naive and gullible, but he doesn't stop thinking and questioning things. That will allow him to no a be fool in the long run, and he'll make his own decisions and develop as a character.
In short, he's a breath of fresh air compared to most summoned heroes in Japanese stories.