It's always the patriarchal conquerors like the Ancient Romans or the Ancient Greeks that they idolize and never the people like, say, the Picts or the Celts or the Gaul that rebelled against the brutal Roman empire. It's never the Scottish or the Irish heroes who fought back against the British Empire that followed in Rome's footsteps. None of them probably even know who Boudica is.
Ironically, a lot of the stuff you could call "white culture" was burnt at the stake, banned, brutalized, and literally demonized by the Empires that chuds think are so civilized. A lot of pagan culture was lost to time, or warped by Roman 'scholars' for propaganda purposes. If they truly cared about their 'culture', then "Muh Christian trad wife' would be seen as killing the identity of pagan women, rather than an aspiration.
I don't think you could easily separate Marx from his predecessors or people who came afterwards. He was very much operating in the western philosophical tradition, his PhD was even about Greek philosophy, his contemporaries were western philosphers. Marx's economic work heavily cites Adam Smith and David Ricardo. Not to mention the modern fields of sociology and anthropology were forged by people well read on Marx's work. I heard someone here once say he was the last Enlightenment thinker, he was the final culmination of that whole group of guys before him like Hegel, Hume, Kant, etc.
But that's just Marx the guy and scholar. You're more correct if you said there are two lines through contemporary western thought: liberalism and Marxism.