WordNet sense 1 (not arrogant or presuming):

unassuming

WordNet sense 2 (marked by simplicity; having a humble opinion of yourself):

modest

WordNet sense 3 (of a person who has held and relinquished a position or office):

past, preceding

WordNet sense 4 (leaving a place or a position):

outgoing

WordNet sense 5 (reluctant to draw attention to yourself):

reticent, self-effacing

WordNet sense 6 (inclined to timidity or lack of self-confidence):

unassertive

WordNet sense 7 (moving toward a position farther from the front):

receding