You forgot a few...Holly Mims, Aaron Wade, Rocky Castellani, Ralph Dupas, Bobo Olson, Jose Basora, Charlie Fusari, Steve Belloise, Kid Gavilan, Bernard Docusen, Tommy Bell, Sammy Angott, Henry Armstrong, Fritzie Zivic, and Marty Servo.
He fought Izzy Janazzo a whole bunch of times, and Jannazzo had a final record of 63(8 kos)-45 (stopped 6 times, three by Robinson, one in his last fight), which isn't much. Until you look at his record and the quality of guys he was fighting, many of them several times, and losing close fights to and you can tell that he could fight more than a little bit.
Look at Robinson's record and how early on he was fighting guys like Angott and Zivic and Servo and you can see he wasn't ever taking easy fights.