LOS ANGELES—Michael Jackson, a talented child performer known for his love of amusement park rides and his hobby of collecting exotic animals for his Neverland Ranch, died from sudden cardiac arrest Thursday at the age of 12. The prepubescent singer, who enjoyed playing dress-up and often referred to himself as "the King of Pop," was celebrated for his naïve exuberance and his generosity toward other children. "This is a terrible loss for music and for all of us," brother Jermaine Jackson said. "He had so much potential to blossom into a gracious and mature human being. As it is, the world will never know the genius Michael Jackson might have become had he grown up." The singer leaves behind a large body of hits, 25,000 unopened toys, and nearly $400 million of debt.