dancing radical (no. 136)
舛 is primarily a radical used in other characters, associated with dancing or opposing movement. Its standalone meaning is unclear and it is rarely used independently.
舛 is thought to depict two feet facing opposite directions, suggesting dancing or opposing movement. The exact historical development is uncertain.
The left 夕 looks like a bent leg, and the right 㐄 resembles another leg stepping in the opposite direction. Picture two feet moving in a dance or stepping apart.
For ブ, imagine a dancer moving to a booming beat: boom -> ブ, and the feet step in opposite directions.