Diamond Sutra: chapter 3
"All living beings, regardless of of their birth; whether they have form or not; whether they are aware or unaware, all living beings will eventually come to Enlightenment. And when this infinite number of beings have all been liberated, in truth not even a single being has actually been liberated." "Why Subhuti? Because if a disciple still clings to notions of duality such as ego, self, or separation, that disciple doesn't see their own Enlightenment.”
The Buddha is telling Subhuti that everyone has the seed of Buddha nature within themselves. We have Enlightenment already and it's only our clouded delusions that prevent us from realizing this. The Buddha is extending this idea, not just to all humans, but to all living beings.