There was not anything about super creatures on the Skynet or the special squad insider materials. It was very likely that humans had never killed a super creature so far.
Maybe some people had encountered super creatures. But since they were not able to kill one, they would never know that it was a super creature, but took for granted that it was an especially strong sacred-blood creature.
When Han Sen first saw the golden growler, he also thought it was just a strong sacred-blood creature and did not realize there was a higher level.
Without any data, Han Sen had to rely on himself to kill super creatures. Without any way to gain a super beast soul, Han Sen had to practice some stronger hyper geno arts.
Han Sen would max out on his sacred geno points one day, which was bound to happen. However, even with all four types of geno points maxed out, Han Sen did not believe he could be a threat to any super creature.