Hercules has been a full God since he first appeared in the Thor comics. Mortals beat gods all the time ie. Hulk (a mortal) vs any god (Ares and Thor). Zeus gave Herc his full "Godhood" when a Centaur tricks Hercs wife into giving herc a shirt with Hydra blood which, in a sense, kills Herc and torchers him (im assuming for what would be an eternity). So Zeus takes pity on him a saves him by giving him his full "Godhood".