In a lot of novels, the characters are only as smart as the author. I’m looking for a novel where the ideas or thoughts of the MC are actually surprisingly clever/brilliant. It doesn’t need to be a novel focused on the MC being a genius; it can be a seemingly normal or generic story with an average MC, but one clever moment surprised you. I found most MCs portrayed as intellectual genius aren’t and don’t think up anything really clever. Most of the time they’re really only called a genius due to their growth speed, plot armor, or cause they are compared to dumbed down villians. I’m looking for any novel where an MC is smart, clever, resourceful, innovative, or just really good at understanding basic things (common sense, like a normal person would stuff) like a protagonist who can give obvious relationships advice like Reika-sama.
Way of the Devil and Seoul Station’s Necromancer they might not seem like obvious choices but those 2 are great at avoiding obvious landmines which seems to be a skill that alot of protags lack.
I'm afraid CN are rather mass production oriented without much thought put into characters. You should fish in the ocean of classic literature to find genuinly well written characters.
If you don't mind published novels, try The Warrior's Apprentice - well, actually the whole Vorkosigan Saga. Not only it's exactly what you're looking for, the writing is excellent. I friggin' love those books.