In its annual listing of the world’s richest people, Forbes magazine ranked San Fernando Valley businessmen Roy E. Disney and Alfred Mann. Mann, 80, is worth $2.1 billion. He is involved in companies that make pacemakers, insulin pumps, cochlear implants, neurostimulators and other products. His latest company, Valencia-based MannKind, is developing inhaled insulin. Disney, 76, is worth $1.2 billion. He holds a director emeritus status at Walt Disney Co., where he worked over the decades as a film editor, writer and producer. His private investment company, Shamrock Holdings, has $2.8 billion in assets under management.