One is a centuries-old idiom. The other is a common way of describing coming from poor origins. The parts in-between are notably different.
No one accused Michelle Obama of plagiarism when she used the idioms without attribution, did they? The most you can say is that their boilerplate is similar.
They were just a few common platitudes string together. But the combination was the same. We now know why and the answer was innocent enough. Story is a nothing burger.