{n. phr.} Not the only person to be considered; one of many. * /George was acting pretty self-important and we finally had to tell him that he wasn't the only pebble on the beach./ Compare: NOT THE ONLY FISH IN THE SEA.
NOT THE ONLY PEBBLE ON THE BEACH
Meaning of NOT THE ONLY PEBBLE ON THE BEACH in English
Slang English vocab. Английский сленговый словарь. 2012