I tried to find the interview you're talking about with the idol mentioning Jungkook as child-like but I can't find it. He's a typical introvert, although apparently he's shy as well. I'm an introvert but am not shy, a common misconception people confuse haha
As for him remaining that of a child, I think, and
I want to make this clear that this is strictly an opinion and not fact, that he might've been abused which is common in the entertainment industry. It's a typical sign of an abuse victim to stop mentally/emotionally maturing passed the age that the abuse started. He joined BigHit at aged 15 and that's when he claims his maturity stopped.
This is a quote from an abuse victim:
"When I was in recovery, I discovered that our emotional maturity stops growing at the age when our abuse began. I first viewed this with disbelief. After giving it much thought I realized that, although I hated to admit it, my emotional maturity level had been stuck at the age of thirteen, the age of my abuse, for many years."
Abuse is a tool used to control a victim. It happens all the time within the industry, specifically with MK-Ultra. Many are brainwashed into thinking it's normal. Now we all know he's from a culture that emphasizes respect for your elders, but that shouldn't mean abuse and I'm sure it doesn't in regards to that. But factor in an industry where you're usually treated as property, this can cause for people to take advantage even more than in the real world. Cultural differences aside.
This video that caused a huge backlash towards BigHit shows what appears to be Jungkook threatening to be hit by a former manager. This seems normalized why he would do this in front of the other members and why Jimin turned around as soon as he probably heard the managers tone and perhaps threat.
So is this all coincidence that his maturity stunted once he joined BitHit and became a trainee? Thoughts/opinions?