Jiang Xingze had his reasons for saying the Silver White Snake was, at best, a Snake Spirit.
His master, Dr. Snake, had once told him that a snake's path to becoming a Snake King was as arduous as the legendary Journey to the Western Heaven. Just as that journey involved eighty-one tribulations, a snake's Cultivation into a spirit and then a Snake King required passing through forty-nine trials. Upon achieving Perfection, the character for "King" would appear on the Snake Spirit's forehead. Only then would a new Snake King be born.
The saying that animals weren't allowed to become spirits after the nation's founding wasn't just a joke.
You've probably seen reports on TV or in the news about an old tree being struck by lightning, with the corpse of a massive snake found hanging from its branches, also struck dead.
That massive snake was most likely a Snake Spirit attempting to leap the Dragon Gate—trying to become a Snake King—only to be struck down by the heavens as punishment.
