In relation to Steiner terms, it would break down like this:
B) Childlike = Crawling/Walking/Tricycle
R) Elderly = Cane/Walker/Hospital bed
Y) Adolescent = Skateboard/Bicycle/Public Transportation
W) Adult = Sports Car/Luxury Car/Limousine/Jet/Astral TravelSo, according to Steiner, a human spirit, incarnating into a particular race on earth was no different than a person being limited to only the transportation options of one of the four categories above. Not so bad if you're in category W (like most Anthroposophists happen to be) - your worst option is a Sports Car - and you can work your way up of course. But let's be fair here. You are not a savage, you are intelligent. You are part of the race of the future - so no doubt, you've earned it. OK, it was your birthright, but still...
While the other categories might not look quite as appealing, according to Steiner, nobody should mind which category he placed them in. After all, the evidence of which category a person belongs in as well as the indicator of that person's physical and spiritual limitations is right there on their skin. So, if the best you can do in this lifetime is a tricycle, that shouldn't worry you. In your next incarnation you may get to bicycle. If you work hard, and embrace Anthroposophy, you may be born into a nicer category next time around, or someday.
For more on Rudolf Steiner and the Races see here, here, here, here, here, here, here, here, here, here, here, here, here, here, here, here, here, here, here and here.