Ramos also wanted to go to PSG, something that Varane by most accounts isn't interested in.
Like you mentioned, those other 2 were confirmed just about before or immediately after the season ended, before the possibility of Varane leaving even started being reported on.
The possibility of Varane leaving has been reported for years, this isn't a new thing. It has also been reported that United were his favored option for years and United being interested has also been reported for years. As Sultan said earlier United is an attractive proposition for a player that isn't looking for easy trophies because he has already won everything, he is looking for a new challenge which United provides in the form of making United great again and United also has the luxury of effectively having as much money as any other club on earth and able to match his financial demands.