If Islam is such a great religion, why did we fail to produce great muslims

Re: If Islam is such a great religion, why did we fail to produce great muslims

so who brought slaves like Hazrat Bilal Habshi (RA) in a position to inquire from a caliph about his spending? Haven’t our history books mentioned how slaves were treated by companions of the Prophet and who got how many slaves free?

For rulers like Omar (RA), isn’t it well know fact that his slave was riding the camel and caliph walking on foot, while they entered Palestine as a conqueror?