So much has been said and written about Elvis, so there is no shortage of reference material. But the bottom line is this:
He was a young kid who did not want to work in a garage. He had a good voice and good looks. He liked the way both the gospel music and the "Negro music" sounded. But his tragic flaw was a desire to be accepted, and he wound up with a con artist named Parker who gave him his dream.
Like most "genie in a bottle" stories, there was a downside. The fame came way too fast for him to handle. (Imagine Bill Clinton in the Oval Office with Monica Lewinsky saying, "Damn, I can't believe I'm doing this. Shazzam!")
His personal physician Dr. Nick was a willing accomplice who gave him every drug he asked for. Often, this was Dilaudid. It killed him as he sat on the toilet in Graceland. His last words were, "Corn?"
But listen to songs like "Teddy Bear" and "Don't be Cruel" and tell me he's not the King. If there's a heaven, he's there with his mom. If not, he died in a trance with no pain. So there's that.
For two great song which will help you understand Elvis, try Mark Knopfler's "Back to Tupelo" here, or the more inegmatic Elvis Costello's "Worthless Thing." Here but just listen; video is crap.