Ron, in canon, wasn't much less bright than Harry: they were both fair-to-mediocre students who bumbled through adventures mostly on the strength of luck, chutzpah, Hermione, and the beneficence of older and more experienced characters. Ron being a non-viewpoint character, though, we didn't have as clear a view on the motives behind his failings, and so they came off as less explicable. On the other hand, he did have that talent for chess where Harry didn't, though we only really see it in the first book.
For that matter, Hagrid wasn't portrayed as especially dim either; he wasn't a particularly educated character, but when the script called for wisdom of an earthier kind than Dumbledore's, he was often the one to give it. He just had a blind spot where dangerous animals were concerned, one that for mysterious plot reasons his higher-ups were happy to give him opportunities to indulge.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 119.
Plans for next chapter release:
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)