The law and common sense have very little to do with each other. Occasionally an intervention is attempted, but it usually goes badly.
And that is why it is so hard to explain these things if you haven't been "programmed" to think like a lawyer. "Natural born" citizenship, viewed historically and not limited to just the US, has had two basic mechanisms, jus soli and jus sanguinis, right of soil and right of blood. Arguably, the founders found jus soli the easier case, but not to the complete exclusion of the other.
The result is twofold:
A) You cannot have "natural born" on a jus soli basis because you cannot have (AFAIK) one "soil" under two sovereign jurisdictions. That would be a non sequitur.
B) However, you CAN be "natural born" by right of blood under jurisdiction X and also be "natural born" by right of soil under jurisdiction Y. It's counterintuitive, but it can happen.
And that is precisely the Cruz scenario. His claim to natural born status for the US is based on the right of blood through his mother. His claim to natural born status in Canada is based on right of soil. It is a case of overlapping legal principles, which, BTW, is a very common occurrence in the law, but often trips up even first year law students, who often assume two things are mutually exclusive, when in fact they are not.
Peace,
SR
It takes two US citizen parents birthing their child on US soil to bequeath a natural born US citizen.
A) You cannot be "natural born" in two countries on a jus soli basis because you cannot have (AFAIK) one "soil" under two sovereign jurisdictions. That would be a non sequitur.