Your post and opinion is painfully narrow-minded, you have absolutely no control over the big picture.
Signing Ronaldo was a "mistake" based on the fact that he will never replicate what he did in the past or for Real Madrid, but damn sure he has scored a few goals and been our best player even at 37. We also signed Sancho this summer, perhaps he could be the big reason for everything bad? What about Varane? You pick and choose based on your simple agenda, your post has no substance.
The big picture for me is that the culture after Solskjær was incredibly bad and on its way down no matter way, signing Ronaldo or not had no impact on this, my opinion is that he is an inspiration for most of the players regardless. Does he get special rules and special treatment? Of course he does, he is a unique player and one of the best players of all time without question - it should however set goals for the not so incredible players. If that riles up absolute dross like Maguire and McTominay then so be it, they are not here for the long-term anyway if we want to be successful again. One thing is if Ronaldo shows up late and lavishes around like a Balotelli-character and misses traning and still play games, but we all know Ronaldo shows up first, leaves after all others and trains like a champion.
I suppose you could read some of my other posts in this thread to get some more substance. There is plenty of analysis there on how our game has changed and how it has affected our numbers, gamestyle and the dynamics of our games.
Do you really think Varane and Sancho has had the same impact in our dressingroom as Ronaldo?
Do you really think we have completely changed our way of playing to fit in Sancho or Varane?
To play a 36/37 year old striker with record low pressing numbers comes with some costs. That means other midfielders and attackers must cover more ground, we won't win the ball when the opponent is off balance as often, we play less direct, we let the opponent enter our half more often, we create fewer chances and we concede more chances. To justify this, the pro's should have been a lot bigger than they have been with Ronaldo. We also become more predictable and one dimensional when attacking. A non penalty goal from Ronaldo every 155 minutes does not justify this sacrifice.
Also, like I've posted plenty of times, Ronaldo is still among the best when it comes to off the ball movement, positional awareness, occupying the right spaces and in general getting into good scoring positions. His allround game has improved a bit again lately, but in general the pros are too few to cover for the cons. And this is just on the pitch.
For some reason there are rumors of clicks and division in the dressingroom. Key players have become shadows of their former selves and most (if not all) players are performing worse than they were last season. It's quite obvious that plenty of players are unhappy now, as opposed to happy 12 months ago. There is most likely many factors playing in here, but if Ronaldo is this great inspirator, rolemodel and motivator, it's not rubbing off. On top of this it seems like the management hasn't been able to capitalize on the obvious resources he potentially could bring to a club as a whole. I'm not a fan of stopgap solutions or buying players past their peak in general and I think it was an extremely short sighted signing from the start. I can't see any scenarios where we become a top club again by feeding the ball to a 37 year old who doesn't press. It just isn't possible in the PL or the CL.