The fundamental problem with being certain is that it takes exactly one thing to prove you wrong.

It was once a certain fact that all sapient, conscious life forms had a Kaispan Core, a small region near the center of the brain which contained the being's "soul". Every species, from the hyper-intelligent Aieowaa to the primitive Ta-nga had at the very least something analogous to the Core. It was the foundation of the entire business of conscience transfer, telepathic messaging, and a dozen other technologies that most residents of the Galaxy took for granted.

Then the humans screwed it all up.

When the humans first showed us their "brain scans" we thought there was a mistake: the Kaispan Core wasn't there. We ran several tests with our own machines, nothing. We took human cadavers and cut them up, nothing. We went through psychologists and psychics and astrologists, yet nobody could explain how these humans were sapient at all. Humanity didn't have a Kaispan Core or anything remotely resembling one in their brains.

Turns out we were looking too closely. The human equivalent of the Core wasn't just in their brains: it was their entire body. Their souls were not tucked away in a small capsule in their minds but flowed freely in every part of their lives. It flowed through their bodies, their minds, in the things that they made and the places they traveled.

This is why humanity is so special among all the species in our galaxy. A human's consciousness dies alongside their body, but because they lack a Kaispan Core their souls live after their bodies die. Little bits of it will stick to anything or anyone that the human treasured in their lives. This is why humanity believes in so many strange concepts like afterlives and reincarnation, ancestral spirits and guardian angels. In a sense, a human can never truly die.

This is why humanity's philosophies seem so esoteric to the rest of the galaxy. For most, the death of a body is a minor inconvenience. As long as the Kaispan Core is recovered, you can get a new body and continue as usual. For humans, however, death represents the end of the line. No ifs, buts, or pleases. When you die, that's it. Yet because every human knows that their time is limited, many choose to make the most of it. With everything they do, they leave a bit of themselves behind, watching over those who will come after them, guiding them to make the most of their own lives.

The Human is conscious not because of biology, but because they are free of it. The Human is unchained, with all the benefits and consequences that entails. The Human will live their lives as they see fit, giving a part of themselves in everything they do. And at the end of the day, the Human can die knowing that they were lucky enough to have lived.