I do not understand what is so disturbing that the United States is a world superpower now, it's better than the period of the amount of superpowers that fought against each other,
Also, yeah america helped in World War 2, but it was really the Russians. However, they only won because of the severely high amount of soldiers they had
My interest of the Islamic Caliphates may be subjective. To satisfy you, replace it with China. They also have a more interesting history than Russia, UK, Germany, and Japan.
I don't see a very long history as "epic", but a diversified and intensiv one with ups and downs, different ages and influence on other countries histories.