Not quite. Nations change. Americans, for example, were once British. The Soviet man is indeed a new phenomenon that has little to do with Russianness as we know it through the centuries. The present population of the Russian Federation, while retained some ethnic Russian roots has acquired a different, ugly mentality on display today.
Whay can’t ‘Russianness’ change through centuries also? I think you have never come across the idea of “Russia as the 3rd Rome” or the Byzantine Christian Empire which were in effect in the Tsarist Russia.