occupy by force, usurp, possess
佔 centers on taking control by force or without right: occupying territory, usurping power, or possessing something aggressively.
佔 combines 亻 (person) with 占, which likely contributes the sound and may relate to the idea of occupying or taking a position. The exact historical development is uncertain.
A person 亻 standing beside 占, like someone planting a flag to claim a spot by force. Think of a person occupying a space and refusing to leave.
For チン, imagine a chin held high as someone usurps a throne: chin -> チン, and the person 亻 forcefully occupies the seat of power.