No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States.

They made themselves some special exemptions when they wrote it.

Okay guys, we finally have our independence! Now we just have to wait 35 years to actually get an eligible president!

He was born in Virginia, parts of which had been colonized for over a century by the time he was born. Unless you mean because the US didn’t technically exist when he was born, but I don’t think there’s any evidence the Constitution intended to exclude people born before the Revolutionary War.

That’s one of those facts that seems like it shouldn’t be true, but I think that’s just because history classes tend to compress so much of the colonial period to jump straight to the Revolution.

it's about allegiance to a country.

if not in place, what's to stop Putin from being elected US president and then annexing it under the Russian federation?

at least for now he had to put his orange bag of shit in place, which makes it far more difficult to control.