Xia Shuqin
This novel doesn't make any sense if he is a transmigrator. The pet would easily feel something off and it would have complications with the bond. The "predecessor" is most likely the mc and he unlocked his past life with the help of a system which means this is a new him, a reincarnation, or just him but his past life's memories just became his dominant memory or something. Either the translation was wrong, the author just used transmigrator because its a popular word or they did not know what tramigrator means.