all, any, every ordinary, common
凢 centers on the idea of something being ordinary, common, or all-encompassing in a general sense. It can mean 'all' or 'any' in a broad, everyday way, and 'every ordinary' or 'common' as a natural extension of that generality.
凢 is a rare character whose historical development is uncertain. It may be a variant or simplified form of 凡, which originally depicted a sail or a general shape, but the exact origin of 凢 is unclear.
The top 丿 looks like a sweeping gesture meaning 'all', and the bottom 几 resembles a common table. Imagine a common table where all ordinary things are placed.
For ボン, imagine a common bonfire where all ordinary people gather: bon -> ボン, and the fire is as ordinary as the kanji's meaning.