Assuming you're not just throwing a tantrum like a child, I've taken you up on your offer and will explain.
First of all, 2nd Childhood is a brilliant, beautiful and cautionary song. Aside from the fact that it sounds fantastic (which is the most important part), it's just really smart. Great theme. The term "second childhood" usually denotes senility: the phase an adult, usually senior, enters into when they need to be taken care of like children. Their mental capabilities are deteriorating. Nas flips this idea to describe perfectly healthy people who are much younger but immature. They refuse to grow outta the dumb shyt.
Straight up, I've never heard anyone use the term 2nd childhood in the way Nas does. On some social anthropological shyt. It's a superb flip. I could be wrong: maybe someone did it before Nas. If you know, please prove it.
So let me analyze the different lines
This is a great 'time lapse' sorta line. You can picture a guy sitting on different project benches over several years. It shows a certain docility in the guy's mind. He aint up to shyt. He's moving but fixed to one point. That is what it means to be mentally stuck.
and the musical chairs part is a great reference because kids play musical chairs. Adults don't really do that.
A really simple clear line that says a lot. That's what you call profound.
obviously we know what this references. I just think it's a good line. The whole verse is about how this girl doesn't really have anything going on in her life. No profession, except giving brains. So calling her the brain surgeon is a biting line.
There's nothing profound about this line on its own, but it's a great 'closer' to the verse. It encapsulates the main problem with the girl in the entire verse. Concise and accurate.
Now tell me how those lines aren't profound