The most significant cultural aspect of 笨 (bèn) is its role in humility and self-deprecation. In many Western cultures, calling yourself “stupid” can be seen as a sign of low self-esteem. In Chinese culture, however, saying 我太笨了 (wǒ tài bèn le - “I'm so stupid/slow”) after making a mistake is a very common and socially acceptable form of modesty. It signals that you recognize your error without making a big deal out of it. This connects to the cultural value placed on effort over innate talent. The famous idiom 勤能补拙 (qín néng bǔ zhuō)—“Diligence can make up for clumsiness”—captures this perfectly. Being 笨 (bèn) is not seen as a permanent, unfixable state. It's a condition that can be overcome with hard work and persistence. Therefore, admitting you are 笨 in a certain task is also an implicit promise to try harder.
The use of 笨 (bèn) is highly dependent on the situation and your tone of voice.