fall, lie down, bend
仆 centers on a person losing their upright posture: falling down, lying down, or bending over.
仆 combines 亻 (person) with 卜, which likely contributes the sound. The character suggests a person falling or bending.
A person 亻 beside a divination stick 卜: imagine someone bending over to cast a fortune, then falling down in surprise at the result.
For フ, picture a person falling with a soft 'foo' sound as they hit the ground: foo -> フ.
falling dead; perishing; dying