It is obviously intuitive, but over the last 15 years or so, players have been hitting their absolute peaks before 30, they've been entering their prime earlier and earlier, but if you look at players prime years, they almost all start with the same amount of seasons into their career and those peaks still remain the same amount of years i.e. 6-10 years is when most players are at their best with around similar production in 11 and 12 before a decline starts. It doesn't really matter if they start at 18 or 23 either. There are obviously exceptions in players that hit their peak years earlier (Jordan for example started his peak in year 3) or that seemingly defy the aging process (Lebron who really hasn't shown much decline 16 years in), but they tend to be the exceptions. That is why someone like Buddy Hield is still getting exponentially better while Irving has been about the same for the last 3 years (his 6th, 7th, and 8th year in the league) despite them basically being the same age.
In the expansion era of one-and-done and high school players, of course some will peak at earlier ages. I think you are conflating several completely different things in order to support your thesis (which I believe is that minutes played are more important than age). As others have pointed out, actual studies have concluded the opposite.
Yes, Buddy Hield is going to grow more at age 26 when it's only his 3rd NBA season vs someone in their 8th season who reached All-Star level a long time ago. Experience and opportunity matter, and so does how much room you have left to improve. An All-Star like Irving can't make a similar leap or he'd be putting up 40ppg right now. This doesn't really support your theory. By age 30 they are statistically like to have the same level of health and decline, and both will have peaked as players. What isn't true is that you'd be better of investing in Hield at that point, to any known statistical degree.
As for peaking around season 6-12... the number of players who get drafted before age 20 into the NBA and then play 12+ seasons is so incredibly small, that you really need to at least cite a substantial list of examples. Years 6-12 is an incredibly wide net for NBA players.
As for LeBron, look at it from the other side: if it was more about minutes than calendar age, then you'd expect the LeBron, Garnett, Kobe group to have outstanding careers up to around age 30-32 and then flash out early. But they haven't -- they "get old" around 35, like other top players who entered the league at age 21-22.