"You know that one guy who is puffy and has glasses and wears a blue purse and has brown skin and says funny things?" ~my son, age 4
It's not something he feels makes anyone better or worse, just one of their descriptors like all of the rest. It's no more important or less important than any of the other descriptors, it just is.
Now, at 4, he knows neither the nuance or great significance of race relations in our society. We've touched on it, we'll touch on it more as time goes by and conversations come up, we'll go on to dig deep in countless conversations to come, because it's part of my job as his mom to do so and part of joy to teach and learn from him.
(...when you're "colorblind.")
Right now, he knows that some people are "cool," some people are "light," some people are "creepy," some people are "puffy," some people are "super loud," some people are "hilarious," and some people are "brown." He knows that some people might fit into a few of those categories, but would never dream of someone fitting into one of those categories because they fit into another. But ya, my son sees skin color. Including my former self, only a fool would say they don't.