Another thing you're all not considering about the girl is that as she got older she got more mature. We can all agree that harry was a Child when the show began and Harry was a child when the show finished, but Kes was getting smarter and more talented and cunning as the hours ticked by at a superluminal velocity compared to ploddy humans and stolid Vulcans, that on the ship by the time she was 5, she should have been able to out Kirk anyone on the ship and smile down on the lot of them as children, yes even Janeway, who are really trying their best and it's just amazing that they can walk upright.
Episode to episode Kes would have been the same woman like B'Elanna was the same woman season to season... You know if the writers had chosen to keep her maturity apace with her dwindling lifespan, in the same way that some one twice janeway's age, Neceyev or Picard would seem to be more capable on paper just because they've been doing the same job for a considerable amount of time longer, that equivlently Kes can learn and master any task, skill or discipline a thousand times faster than a human.
Caretaker must have been putting thorazine in their food to keep possibly millions of people just like this content living in a box under a desert with no relief.
y'see, Seven an Kes could have come to have both known just about everything, except that Kes had put her shoulder to the wheel with curiosity that kept pace with her retention, unlike Seven who was raped in the brain until it was loaded down like a data mule with unwanted cybernetics and information, which on the off chance just happened to be useful after the fact.