IMHO look at decades preceding the 14th Amendment. For example, one reason we went to war with England in the War of 1812 is because England would capture American sailors (some say a total of 10K within 10 years) and force them to work on British ships (impressment). To be fair, some of the "Americans" at that time were Brits who had left England to come to America, never became naturalized citizens, and, therefore, were subject to the English draft laws as any other Brit. Thus, those men weren't "subject to the jurisdiction" of the U.S. but instead were subject to the jurisdiction of England. In other words, those men had to obey England even though they were in the U.S. (I'm not talking about the American citizens the Brits impressed because they looked like Brits. I'm talking about the British citizens the British navy impressed because they had to serve in the military like other men.)
That doesn't mean that immigrants back then didn't have to obey our laws regarding theft or murder or such. It just means that there are some laws that citizens have to obey of their country of citizenship regardless of where they live (at least back in the 19th century when the 14th amendment was written). IMHO, that's what "subject to the jurisdiction of" means. It means, which nation can draft you into their army (or other things a citizen is required to to) or which nation you can vote for, etc.
“IMHO, that’s what “subject to the jurisdiction of” means.”
The problem is that it’s just your opinion. The plainest reading of the word “jurisdiction” is how we use it every day. If a country (or state, or county, or municipality) can charge you with a crime for disobeying their laws, then you are under its jurisdiction. That’s the “normal” meaning of the word, and absent any indication to the contrary, we don’t really have any reason to think the authors of the 14th amendment meant some other interpretation of the word.