Stone Age and Lords of Waterdeep are the quintessential “My First Worker Placement” games and I have a hard time disagreeing with that. Stone Age in particular would be good for a younger audience. There’s a My First Stone Age (or something like that) and I know literally zero about it, including the suggested age range.
[tongue in cheek] My favorite “Worker Placement” game is Men at Work [/tongue], but that’s a whole different subject (buy Men at Work, totally worth it!)
I’ve found that pure “worker placement” games are somewhat lacking in their ability to capture my attention. I enjoy Agricola and I’ve never played Caverna or any of Rosenberg’s other WP games (Le Havre is on my shameful shelf). I did find, however, that variations on worker placement are more to my tastes. Village is not quite WP but is really quite good. And Castles of Burgundy and Troyes are both dicey WP variants which are both widely loved and worth checking out (Troyes probably not suitable for a 10yo, CoB would be debatable with a 10yo)
TL;DR - Check out Stone Age and see where that takes you. Aiming at 10yo-friendly WP games is definitely a challenging shot and I think Stone Age is your best target, at least initially.