How does Harlan Ellison use imagery in Jeffty Is Five?

Imagery:

What I mean by five years old is not that Jeffty was retarded. I don’t think that’s what it was. Smart as a whip for five years old; very bright, quick, cute, a funny kid.

But he was three feet tall, small for his age, and perfectly formed: no big head, no strange jaw, none of that. A nice, normal-looking five-year-old kid. Except that he was the same age as I was: twenty-two.