We picture our speaker as anywhere between the ages of 35 and 60. He's not really young or really old (which fits into that in-between places feeling he has in the poem). Sitting next to him on the plane, you'd probably not give the guy a second look. He's typical. Boring, even.
But hey, at least he's literary. The guy is reading Moby-Dick after all. In fact, maybe he's not so ordinary after all. We can tell from his reading that he's got quite an imagination, and it seems like that goes all the way back to his childhood, when he used to look up and admire the planes in the sky.
So sure, he may be typical, but he wants his life to be anything but. And he's got the imagination to make that happen.