In the exchange between Rachel and the zombie, the zombie was actually forced to retreat. And he did not retreat simply without any injuries, considering that he actually felt like his hand had already been fractured.
Feeling the intense pain that was coursing through his hand, he looked at Rachel who looked excited without any injury, ready to attack with horror in her eyes. He had not expected that he was going to encounter a situation like this. Additionally, the one that he was facing was none other than a human, the one that they looked down on.
According to the calculations of the superiors of his race, they thought that sending him and the other two would enable them to be able to take over this world quite easily, obtaining the benefits that came with conquering the world. But they had not expected that they were going to encounter an abnormal situation like this, where there was a group of humans that had already reached the divine rank.