They didn't change their minds two years later. They just did a sh*tty job of writing it down the second time around.
And for what it's worth, there is an interesting story behind how the words were changed, and it centers around Senator Howard learning of this thing called "Temporary allegiance."
You should look that up. Senator Howard describes how they went from clear and sound verbiage, to the craptastic garbage that actually became the 14th.
I ran across it years ago. Might have been Trumbull. I am now vague on the recollection.
The 1866 comment says nothing of the words of 14A. You choose a comment about a prior statute law because you prefer that to what was said about the words of 14A upon introduction of the Citizenship Clause. Which part are you not able to comprehend, “all persons born” or “subject to the jurisdiction thereof”?