> Yet I distinctly remember kids from my childhood who could not hold a conversation, they would literally break off into a new topic while you were mid-sentence with them.

I have some variant of this - I'm constantly, subconsciously cutting in during someone else's sentence just to blurt out what immediately came to my brain, because I usually forget it by the time they are done. It's something I'm really working on, but it gets better day-by-day.