Childish vs. Childlike

This is on the 7. I'm on Third, slowing down for the wire at Cherry. A thin, older African-American fellow stands up and says in a reedy voice, "can I tell an innocent joke?"
"Please!"
"You make riding the bus a pleasant experience."
That was all. He meant it. I didn't think this statement qualified very well as a joke, but it was definitely innocent. I looked at the man's face, and on it was an open, bald honesty I almost never see. He had the long gaze older people sometimes have, but there was something else too.

It was the sincerity you get from a child who hasn't been hurt yet, who doesn't yet know the pain of wearing yourself on your sleeve. A sentiment from another world, one without irony, without cynicism and all the rest. And yet, looking at the wrinkled lines framing his eyes, the leathery hands and fading silver hair, you knew this person had seen things, been hurt and loved, and experienced the glorious and terrible extremes of life in the modern age. He was not a child. But he had the ability to be fully open before the world, wide-eyed, without the protective armor of anger or resignation. Such a thing is not easy. I admire that.