But nothing makes me smile like being able to witness the purity of joy and awe as someone learning something new. Child or adult doesn’t matter, but children show it more cleanly and plainly IME. I like helping and I like educating.

That is wonderful and I'm genuinely delighted it brings you joy. The world would be a far better place if there were more people like you in it.

Does that make me moribound? Because I get a dopamine hit when I spread knowledge and understanding?

No. It makes you moribund if you need another person there with you to enter a "great and absorbent state of mind". For me the annoyance of having to watch over a kid far outweighs any potential joy I could derive out of educating them or watching them learn something new, which is why there is no place I would want to go or experience I would want to have that would be made better with the presence of a kid. It's that simple.