Cristiano once said that as long as he can still run on the pitch then he will not retire, but he seems to have realized that old age makes his stamina decrease and it would be great if he didn't become a starter. Manchester United management always expects Cristiano to give good results in every game he does and what ten hag has to do is give Cristiano more playing time.
Ronaldo is the best player in united and they will do anything to reserve him in the club in the January transfer market. His presence alone put fear in the mind of defenders. Ronaldo is aging but he's still dangerous as of when he was young. So much respect on his name and Erik ten hag will be giving Ronaldo playing time now that he knows that he would give him positive results. United might likely end in the top four this season because they're trying to win games.
I think you are overestimating Ronaldo here, if Ronaldo is able to scare all the opposing team's defenders, it is impossible for Manchester United to get a draw and lose. One goal obtained by Ronaldo when he beat Everton did not become a benchmark for Ronaldo as the most important player in the Manchester United squad.
Ronaldo's age has made him unable to perform like he used to, now Ronaldo can only rely on experience when given the trust to play. Ronaldo is not able to run as fast as he used to, his strength has also started to decrease, for this reason Ten Hag put Ronaldo on the bench more often than installing him as a starter.
Yes, he's overestimating Ronaldo because now there are rumors about several teams who are interested in signing Ronaldo in the January transfer market and one of them is Chelsea. I personally don't believe Ronaldo will stay at Manchester United until the end of the season so yes, I believe the rumors will probably come true. Also, whether Ronaldo is in the Manchester United squad or not, Manchester United will still have a chance to finish in the top four. So yeah, I personally don't really consider Ronaldo to be an important player now because after all Manchester United have a regeneration that it's time to have younger key players.