This is one weird cover; given this organization's repeatedly botched predictions as to when the "end" would come, I would say they're taking a huge risk with this kind of cover. It's like a big reminder that so many lives have gone by w/o their predications happening. Also, it's clear that the WT art department has few, if any, trained professionals who stay current in the industry. As another poster observed, this is a pastiche spanning the 20th century, yet supposedly organized to show a single life. The little boy in the knee pants is from very early in the 20th century; early 1920's I'd guess and he looks to be around 10 years old. That would make him born in...OH WAIT...that would make him born in 1914!!!
The boy with the bike looks like 1930s, as has already been noted. He looks to be in his early to mid teens, born around 1920. The guy with the dishes is from the 1950's, the guy with the briefcase, maybe the 1970's. There's no way this could all be one person, yet that's ostensibly what it's portraying. Are the artists so out of touch with how people live that they really think someone who would wear a cap and knee pants as a boy is still alive, albeit hobbling around with a cane? The old guy might be in his eighties, at the most. And yet if it's not supposed to depict a single life, what's the point? Why display it in this manner? Because of this anachronistic depiction, the picture has a decidedly creepy feel...
Also, so many of the pics the WT uses show the "representative" white, middle class male, as if somehow that represents the "majority" of people, either gender-wise or economically.