The multiheaded hydra Hercules reputedly slayed during the second of his storied 12 labors has become a band of marauders disguised with serpentine masks. If the gods exist, they’re nowhere to be seen here. Condal and Evan Spiliotopoulos have sanded down many of Moore’s rougher edges (including his Hercules’ volatile temperament and bisexuality) for this more family-friendly enterprise, but they’ve built on the idea of the warrior hero as a self-conscious mythmaker, inventing practical, real-world explanations for all of his seemingly superhuman feats. Ratner’s film owes its counter-canonical premise to the late author Steve Moore, whose five-issue Radical Comics series “Hercules: The Thracian Wars” proffered a Herc who was markedly more man than god, his supposedly divine paternity a useful legend but perhaps no more than that.