Big Man On Olympus

SO LONG, SUPERMAN; HERcules is the demigod du jour. MCA TV's delectably cheesy ""Hercules: The Legendary Journeys'' (with Kevin Sorbo as the quarterback of Mount Olympus) has slain ""Baywatch'' in syndication ratings. In August Scholastic will offer kids ""Hercules: The Strong Man.'' Marvel Comics will feature the mighty half-mortal in ""The Hulk vs. Hercules'' special issue at summer's end. And Disney is hard at work on an animated ""Hercules'' for release in '97. Why Hercules instead of, say, Aquaman? Explains ""Mystery Science Theater 3000'' star Mike Nelson (whose show lampoons four old Hercules flicks): ""We need a hero, be it King Arthur at Camelot or Hercules in a tiny animal skin. We also need something for late at night, when we tire of Abflex TV commercials.''