Some people say that Cicero was born at the wrong time, I say that Cicero was born at precisely the perfect time.
It was crucial for Cicero to have been a post-Sullan lawyer. Not pre-Sullan, not post-Caesar, but specifically in the time period of around 81 BCE to 49 BCE. Before this time period, and it would've been hard for someone like Cicero, a new man, to have broken into the ranks of lawyers (who mostly belonged to old families) and there were also quite a lot of them, so it would've just been hard for him to get his foot in the door. As well, it seems to have been less conducive of a time for the law to help with one's political career, possibly.
If he was from after this time period, such as the principate, the justice system had changed and it just wasn't a good place for a Cicero. Roman lawyers of the later time periods all say that Cicero couldn't have handled this time period, since the super long speeches (as well as allowing the lawyers to do whatever they wanted) was part of an older time.
The most important thing about him is how old he was around 81 BCE, aka when the justice system started working again. Right before this, a large amount of lawyers either got murdered or decided to retire. And so, at 81 BCE, the field was pretty sparce, and perfect for someone like Cicero to get their foot in the door.
And so, the trial of Roscius, the first murder trial in years, was the perfect opportunity for Cicero to make a name for himself. It wasn't actually his first case (it was his first criminal case) and in my opinion, its importance in society as a whole has been exaggerated (although it was SUPER important for Cicero) and I am not exactly sure about what I'm saying; honestly I am just yapping for the sake of yapping. But what I want to say is that so much of Cicero's success came from being born at the time he was.
For example, Hortensius was born eight years earlier, and because of that, he got to start a short but glorious legal career right before the social war ruined everything and he was drafted. He came back once things went back to normal, but he could've had a much better career if only it hadn't been cut down so early.
Or maybe I am wrong. I don't know. I should be studying for my DELF right now. Why is it in under a week??