This is my theory: remember how the cat system said that all the older systems got promoted or left, because one of them tried to leave their system role and become human? And that's why the current systems are all animals? And then those little flashbacks/memories where Qin Xian is human transmigrator and he has a human system who looks like Wang Yi? I have a hunch that Wang Yi must have been the system who tried to become human, but lost his memories in the process. Qin Xian must be the No.1 transmigrating villain who only used mind-reading powers but he probably got caught in the transmigration world looking for his lover Wang Yi.
i have a feeling this one is the original guy who had also been a transmigrator like our wang yi is now OR the circumstances that wang yi believes that he entered the system through ARE ALL LIES and he actually has been in the system longer (⊙…⊙ )