pebble
not the only pebble on the beach not the only person to be considered in a particular situation; (of a former lover) not unique or irreplaceable.
☞ This expression is from an 1897 song title: You're Not The Only Pebble On The Beach. The original context was that of courtship: the way for a man to advance his suit was to make it plain to the woman that 'she's not the only pebble on the beach'. It is now often used more generally as a warning against selfish egocentricity.