It could be that the idea of someone claiming to be the dumbest alive sets up an expectation of humorous situations or misunderstandings. Also, the contrast between such a statement and reality often leads to comedic moments.
Maybe it's because the phrase sounds so self-deprecating and exaggerated, which can be seen as funny and comical.
I think it's considered a comic because it's an extreme and unlikely statement. It might make people imagine all sorts of funny scenarios where this person's supposed 'dumbness' leads to hilarious outcomes.
Chapter 243, "How Could It Be Her?!", is the clearest early answer because it turns Flash Change's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Hahaha, the young master's face has gone white, but I got a scare...
Chapter 338, "The Adulterer is Far on the Horizon, Yet Close Before the Eyes", is the clearest early answer because it turns Mom's situation into a concrete plot event.
Chapter 196, "I am the one with the most potential!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. The chapter gives readers a real answer by opening on Wen Jiaojiao was on the verge of a breakdown.
Chapter 4, "She Can Actually Tell Fortunes?!", is the clearest early answer because it turns Lin Manru's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Qiao regretted her words as soon as they left her mouth.
Chapter 95, "The Problem Lies with Your Boyfriend", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on Hearing others praise her daughter, Aunt Lin was smiling so wide she...
Chapter 61, "Young Master Before vs After Going to the Countryside", is the clearest early answer because it turns Countryside Hahahaha's situation into a concrete plot event.
Chapter 214, "The Last Day", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. Early on, Director Sun fell silent for a second.. By the end, Even when Wen Jiaojiao fanned Richards' face frantically, he remained....
Chapter 182, "Director Sun Still Knows How to Stir Things Up", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on At this moment, Qi Tianyu, who had just arrived in the Capital,...
Chapter 348, "Scheming and Being Schemed Against, East Ridge Five, Zhu Yang's Threat, The Dust Settles (Part 2)", is the clearest early answer because it turns Zhu Yang's situation into a concrete plot event. Early on, Lu Yang of East Ridge, ready for your instruction!" As number three's.... By the end, Zhu Yang also stood up, glaring at Zhao Hu with a particularly unkind....
Chapter 60, "The Human Oil King", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter gives readers a real answer by opening on What's with Jiang Yan, treating his own sister Jiang Li like this?"...