As the Barbarian King used his technique, Wang Wei was able to notice the changes in his body, allowing him to know why he was such an anomaly and solve a mystery that puzzled him. From what Wang Wei knew, the Giant Race had been extinct for a long time; they existed in a time that could be described as ancient history even by this world's standards.
The current Giant Race is the product of evolved Creation Lifeforms and has nothing to do with its ancestors. So, how did the Barbarian King acquire his bloodline? He could have found a relic or inheritance of the Ancient Giant Race and acquired the bloodline. However, the chances of anything related to them still surviving in the modern era were slim.
The only other explanation is that one of the Barbarian King's distant ancestors had some affairs with the Giant Race, and the Barbarian King accidentally won the bloodline lottery, awakening that Giant bloodline countless Yuan Epochs later.
