TwoSix
Programs in KOBOLD
And really, the only thing that prevents those newer races from being picked even more is simply that the race options are spread among several different books, and aren't bundled into a nice neat list (outside of D&D Beyond).So. coming in way late:
The circus troupe happens because if you have a menu with 20 items on it and 5 people ordering you're unlikely to see multiple people pick the same item (unless it's particularly tasty) and there's just going to be menu items people don't pick.
D&D has over 70 options.
It's just a matter of math. If there were 9 options, total, you'd see more humans. But with every new species added across every new book the odds of that shrink ever further as people try new menu items.
In Daggerheart, where the dozens of races (ancestries) are presented on cards, with art and all the mechanics printed in one place, I've only seen one human in 12 characters that have been rolled up.