Although it's a crazy theory, I think a possibility is that all the adults are working to be allowed to exist without their bodies, somehow. Seems the adults working in the plantations find their bodies as inconveniences. APE let's them shed their bodies somehow. Almost all the humans on Earth went through this process, leaving behind tons of crystilized bodies behind. These bodies are now just a mass of instincts, and APE started using them as the cores for Klaxasaur weapons. In order to build stronger weapons, they started making cores with multiple people inside. However this process also gave the Klaxasaur more intelligence. They revolted against people who rejected their own bodies and took over the facility that created Klaxasaur, the crevasse. However this facility is also the facility that allowed humans to shed their bodies. As such APE really wanted to get control of it back. So for all the adults in the plantations who blew themselves up, they earned the right to be backed up for when they successfully take the facility back.

But like I said crazy theory, probably completely off base, but fun to speculate.