Examples are endless, even today.
José Mourinho only had a seven year pro career and spent it mostly in the Portuguese 2nd League.
Arsene Wenger only had a six year pro career and spent it mostly in the French 2nd League.
Jürgen Klopp played almost his entire career at Mainz, either fighting relegation or playing in the German 2nd League and wasn't a remarkable player.
Louis Van Gaal played for several mid-tier Dutch teams and was never close to being capped.
Unai Emery spent most of his career playing in the Spanish 2nd League.
Jorge Jesus played sporadically for mid-low tier Portuguese teams.
Joachim Löw usually played in the German 2nd League.
Carlo Ancelotti and Antonio Conte were more high caliber, but they were never stars either, just starters for high caliber teams like Roma, Milan and Juventus. They were capped 26 and 20 times, respectively.
Pep Guardiola, Diego Simeone and Zinedine Zidane are exceptions, but only Zidane was a full fledged superstar among them. Guardiola and Simeone were strong leaders on the pitch but they weren't carrying their teams.