retiring

(s) not arrogant or presuming
- unassuming to a fault, skeptical about the value of his work
- a shy retiring girl
unassuming,
(s) of a person who has held and relinquished a position or office
- a retiring member of the board
past, preceding,
(s) reluctant to draw attention to yourself self-effacing, reticent,

unassuming past preceding self-effacing reticent