Where did ORIGINAL/REAL Rock n' Roll originate from?

After WW2, people had a weight,lifted off their shoulders. They needed an outlet,"rock and roll" ,was the outcome. It's about blues and rhythm and blues and jazz,combined with electric guitars amplifier's. My god,the Stones,Beatles,and Led Zeppelin, copied the blues. Modern day stuff: Aero Smith,White snake, come to mind... Rhythm & Blues,are an American gift.....