This is historically ignorant and reductive. Both men were very cunning, but while Cromwell was not a good guy in my opinion and did a lot of Robespierre-esque things, Stalin is only bested by Mao Zedong in the mass murder department. He was one of the most evil men in history, and if Putin truly wishes to understand all Russians and not just the permanent political class which in the DUMA does include a large cadre of communists, he may need to get out of Moscow and visit the small villages where people still bear the scars of the Soviet Union’s gulag program.
Comparing Cromwell to Stalin is like comparing Mandella to Hitler. They’re not even in the same league.
Probably the one silver lining, if it can be called that, is that Cromwell was still a practicing Christian, so he’s still better than Robespierre and especially the likes of Lenin, Stalin, and Mao where they were atheists and slaughtered any and all religions to show that religion was meaningless.
As far as Mandela, you’re right, they’re not in the same league, if anything Mandela was even WORSE.