The giants were not the only protector of the gate of the Valhalla. Having the opportunity to guard the door was something that all the divine blessed races would kill for, so it was impossible for the giants to monopolise this privilege.
But the giants had actually managed to do just that for a decently long period of time. And the means they used to do that was their incredible power. In the last 10 thousand years or so, the giants had taken care of the gates of the Valhalla for more than 7000 years. That was the reason why the giants had became synonymous with the guardian of the gates of Valhalla.
The gods had created a method to select the guardian race for the gates. And that method was direct combat between the young generation of the races. Other than the giants, the dragon race, the Devil Beast race, the Diabolus race and many more took part in this competition.
