With Fred and McTominay together with a back four behind them, that means only four available spots for any combination of Ronaldo, Sancho, Martial, Rashford, Greenwood, Cavani, Van de Beek, and Jesse Lingard.
Ronaldo and Sancho are both players that are arguably world-class, but were they needed? United scored the second-most goals last season in the league, with 73, exceeding their xG (63.17) by nearly ten goals. Outperforming your xG by a margin this large means that you have a squad with great finishers on it. And while a plethora of attacking talent can be a good problem to have, that is not the case when you do so instead of meeting a more vital need somewhere else on your roster. United's insecurity to let Ronaldo go to Manchester City and their inability to avoid the peer pressure from their fans to sign Sancho certainly won't hinder their progress, but I'm not sure it really adds to it.
So then what about Varane? United definitely needed a center back to pair with Maguire that could replace Bailly or Lindelof. A good partner for Maguire would be a super athletic center back that can make up for Maguire's lack of footspeed. And while that may have been the case early in his career, Varane may not be that guy anymore as he is beginning to age. Nobody should act like this Varane is the same one of the past, at least not after his recent Champions League and EURO performances. Looking to Dayot Upamecano or Edmond Tabsoba may have been better, but only time will tell. United's lack of focus to address their midfield will cost them severely. They didn't have to go out and buy a world-beater, just someone athletic enough to cover space and make up for Pogba, Fernandes, and/or Van de Beek. The obvious answer was always Wilfrid Ndidi.