I can't understand a sentence with "never more ~ than ~"

I'm a student studying English and I'm not quite sure that my question is proper to this site. Let me know if my question is improper.

Thomas Jefferson was never more typically a child of the Enlightenment than in his youthful conviction that reason and inquiry may lead man away from whatever is false, twisted, and capricious in human affairs toward the truths inherent in the nature of things.

The above is the full sentence, and I especially can't understand the following parts.

Thomas Jefferson was never more typically a child of the Enlightenment than in his youthful conviction.

I want to know grammar used in it, and want to know interpretation or rephrasal in clear meaning.

The key to interpreting that sentence is understanding that it is referring to time.

In the words "never more" there is an assumption that Thomas Jefferson lived for many years, and "than" is comparing those years to his youth. Specifically, it is comparing his conviction about Enlightenment ideals as a young man to how he felt or behaved in later life.

Thomas Jefferson was a person born during, and affected by the Enlightenment. This was most evident during his youth when he displayed conviction (presumably about Enlightenment ideals).

Personally, I think the use of the word child and youth in that sentence is part of what makes harder to understand than necessary.

The sentence means that Jefferson was most typically a child of the Enlightenment in his youthful conviction. It could be put more simply as Thomas Jefferson was typically a child of the Enlightenment in his youthful conviction. The addition of never and the use of the comparative adverb (more typically) followed by than tell us that in no time in Jefferson’s life was this truer than in his youthful conviction.

To see how it works, take a simpler sentence: I’m never happier than when I’m studying English. That means that there is no time in your present circumstances when when you’d prefer to do anything other than study English. If you say I’m happy when I’m studying English, that certainly tells us something about your enjoyment of the subject. But, much the same as with the sentence about Jefferson, the addition of never and the use of, in this case, the comparative adjective (happier) followed by than tell us that there’s nothing you’d prefer to do to make you happy than study English.