There isn’t really anything constant about you.
You are a continuous biological process. Your body and mind are constantly changing. Other than that, there’s essentially nothing about you that’s constant. Your cells today were not your cells in the past. The “you” that exists right now will die slowly as it changes into what your body and mind call itself in the future.
“You” aren’t even wholly you thanks to your Microbiome.
The Soul
This is unless, of course, we discover something like ”the Soul”. However the Author of Homo Deus doesn’t believe that such a thing exists.
Split Brain
In split brain patients we’ve observed results that suggest that the two halves of the brain have gone on independently developing, sometimes in slightly different directions. The one person has become two. Interestingly, the person with the half of the brain that controls speech has been seen to create narratives that explain in rational terms the behaviors of their other half based solely on the speaking portion of the brain’s observations of the outside world. It’s possible this tendency to weave narratives out of facts is innate, and also what causes us to dream.