From this, it's evident that the Primordial Giants at least have the qualification to battle the gods.
And speaking of it, the Dark Giant Dragons are actually native creations.
They were originally the offspring and believers of the Dragon Guardian Bahamut, but were enticed by the Dark Force and became Dark Giant Dragons. Because of this, they were cursed by the Dragon Guardian, eternally losing the dragons' magic that dragons took pride in.
Perhaps to proclaim the legitimacy of the victors, the Mortal Kingdoms somewhat embellished the prowess of the Dark Giant Dragons, and after the Numelin Elves left, the sacrifices and efforts made by mortals for the peace of Eteliria. Although the blood shed by heroes, indeed the mortals paid not a small price to achieve the final victory of the war—Oathkeeper, Yoshude, Lady Misu, Mr. Mazak, and even Miss Eve, they were all heroes of this war that continues to this day.
For this reason, such a depiction is not unjustified.
