It was Fall Out Boy’s last album that claimed they were going to Save Rock and Roll, but it’s their latest, American Psycho/American Beauty, that’s coming closer. Although both debuted at No. 1 on the Billboard charts, it’s the former’s lead single, “Centuries,” that has managed to crack the Top 10 — not only the band’s first trip there since 2007, but also the first time a rock group has snuck its way into the spot since Imagine Dragons dropped out more than a year ago. So how long are they going to be remembered for their role in rock’s salvation? The Post’s David Berry cancelled a public recitation of Percy Bysshe Shelley’s “Ozymandias” and sifted through the sands of time to find out.