Then the person showed him the process of how the experiment of humans was done. Starting from the very beginning.
The military personnels, right after the infested alien species spread its black life killing fluid, they separate the chosen humans and those they will put to death.
Almost half of the human continent was consumed by the infested alien species. All life forms were killed. The military personnel, to protect the other half of the continent, created a boundary that separates the infected continent from them. Then they built military fortresses on these boundaries.
But the mecha alien species found a big problem. None of them could withstand the corruption when their skin come in contact with the black fluid produced by the infested alien species. What's even more alarming, are the forces of the infested alien species. Cores started to form and produce life forms mold from the black fluid.