As a mortal Hercules was powerful enough to defeat Ares in battle and force him to flee both in ancient times and modern. Hercules was already far stronger than Ares. He possessed some degree of invulnerability as well. Ares had a few physical advantages depending on the writer like stamina and weather resistance along with a healing factor. If all Zeus did was grant Herc the standard godhood package or remove the mortal part (that was implied in the Pak series) that was holding pak Herc's power then Herc's power comes from just naturally being far more powerful than Ares.
You may be right but I don't recall any incident in which mortal Hercules was able to defeat Ares. Mortal Hercules had some level of invulnerability but it was no where near that of Immortal Hercules or Ares. Mortal Hercules had great stamina but it was no where near that of immortal Hercules or Ares. Mortal Hercules is stronger than Ares but he can not take the punishment that Ares can. In a prolong fight mortal Hercules would die.
Before Pak's story, there was a story when Zeus stripped Hercules of his god hood. Hercules was part of the Avengers and a solo character at that time. As a mortal Hercules was still a powerful brick but his overall power was below that of Ares. Pak tend to butt kiss the character he is writing. If Pak wrote Squire Girl she would kick Silver Surfer's butt.