So as far I understand, the term third Reich comes from
1st Reich: Holy Roman Empire
2nd Reich: German Empire
3rd Reich: Nazi Germany
But how does it make sense to count HRE as 1st of anything? Wasn't the whole point of HRE to claim the prestige and legitimacy of the original Roman Empire?
You could say that they are only counting German Empires, but HRE was a Charlemagne's creation, and hence at least partially French, whom Germans saw as a natural enemy. Not to mention the Italians and Czechs who were at times part of the empire.
I get that Nazis had very selective, flexible, and delusional understanding of history. But their choice of 1st and 2nd Reich makes no sense.
The Frankish Kingdom/Empire co-founded by Charlemange (Karl the Great) was created by the Franks. The Franks spoke Old Franconian, a germanic language most closely related to modern day flemish/dutch. Early on, the Franks were definitly germanic.
The HRE - an offshoot of the Frankish Empire - was definitly germanic with some slavic and latin populations.
Im not well informed about Nazi racial, cultural and political ideology, but from a pro-germanic stance the Roman Empire makes no sense. It is not part of the germanic canon so to say. If anything, the germanic peoples are partly to blame for the Roman collapse. That leaves the Frankish Empire and the HRE as the original germanic political entity. And since the Frankish empire evolved into France, that basically leaves the HRE. It makes a lot of sense to me to call it the First German Reich. The HRE also makes sense location wise. It covered all the central germanic lands.