Zidane and Pep Guardiola have their own uniqueness, even though Zidane was able to win 3 Champions League trophies but he only got it with one team namely Real Madrid, unlike Pep Guardiola he was able to get it with two different teams namely Barcelona and Manchester City even though it took enough time long ago gave City its first Champions League title.
Although these two managers have very different personalities, I would choose Pep Guardiola over Zinedine Zidane several times. Pep Guardiola has proven himself worthy after breaking records by winning the Champions League trophy with two different clubs, as opposed to Zidane, who only did so with Real Madrid, even if it was back to back. Sometimes I think Zidane is just lucky, but it also has to do with expertise, which he could have earned him that as a manager.

Firstly, from any "ordinary club" you can make a top club if you pour in billions of dollars. Even if you create a club completely from scratch, there will be a result. Secondly, City were champions before Guardiola and they will be champions (if they are still not punished for fraud) after him. I don't see that Guardiola is the backbone of City's success - the real backbone is money.
You are correct, but without a strong coach to handle the squad, no amount of money can buy you trophies, even if you sign all of the best players in the world. Manchester City were champions and doing well before Pep Guardiola arrived, but his presence has boosted their spirit and given him the honor of being termed the club's backbone.