You yourself here say it was his mental game and decision making which were his weaknesses. Both of us agree in that regard. I'm disregarding that when talking about his pure talent, whereas you seem to be including that as part of the full package. To me, the mental side of the game doesn't come into it when we are talking pure natural talent. Talent sets the bar as to how good they could be if things go right. The mental side of things is then the deciding factor (or the biggest factor anyway) to how close the player gets to reaching that bar.
It also has to be noted that Martial's biggest weakness is also his mental game and decision making, albeit in completely different ways. His final product once actually in good position is far better than Ronaldo's was. However he doesn't have anywhere near the drive or will to win that Ronaldo always had even at his most frustrating points. Ronaldo's decision making could be utter trash at times in those early years, but his willingness to pick himself and keep trying is something that nobody could dispute. Whereas Martial...unfortunately it's relatively easy to take him out of the game if things don't go his way. Although once again I'm not including that when talking about his talent.
Important to note that I said 'relatively little talent when compared to his peers'. By peers I mean the other players amongst the best in the world, which is exactly what you are doing by saying he had less talent than Rooney and Martial. Obviously you don't think he had little talent compared to the average player.
Nobody saw him becoming the type of player that he ultimately did become. Many saw that he had the potential to reach 'best in the world level', although it was expected to be as the kind of player that he was in 06/07 - a devastating winger who scored a good amount of goals. As a couple of seasons went by and he didn't make the kind of improvements that were expected, many 'lost faith' in him and thought he'd piss his talent away with poor decision making. And yes, at that time Rooney was believed to be the better player both currently and most likely for the rest of their careers. Then in 06/07 it all came together and Ronaldo became the player we knew he had the potential to be (which was the best in the world). Then of course he surprised us all in the seasons following that and reached a level that nobody expected, slowly changing his playstyle as he did to become arguably the greatest goalscorer of all time. Certainly nobody expected that.
Ultimately, as KM said above, most in the early days considered Ronaldo to be a Neymar level talent. That is a good comparison. He ended up going even further than that which is what surprised people, and is part of the under-rating his talent which I was talking about. Saying that he wasn't as talented as the other players who are amongst the greatest of all time, and that it was his mentality and drive which allowed him to do so? Yeah, that's fair enough. Saying that he wasn't as talented as Rooney or Martial? Nah, that's just not true. I guess I can understand you saying Rooney as it was somewhat close, but Martial?