First-time director George Huang, 27, appears to have everything a Hollywood up-and-comer could want: six years of experience at major studios, friends in high places, and now, an impressive feature debut, Swimming With Sharks, about an assistant who gets even with his despicable studio boss. But Huang's first brush with success is breeding paranoia in other people. ''The most disconcerting fallout of this experience,'' says Huang, who counts notoriously prickly producer Joel Silver among his former employers, is ''that a lot of people think this evil character is about them.'' Does this mean he'll never eat lunch in Mortons again? ''No one will hire me for a day job,'' admits Huang, whose personal investment in Sharks has forced him to move back into his parents' house. ''I don't know why.''