Older kids teaching younger kids is normal.
They are stepping up toward adulthood.
There isn’t much opportunity for that in an age-segregated and prison-like K-12 school.
The notion that “YOU ARE 8, and must ACT 8 is foreign to me”
You are 8, so you must hang out with 8 year olds.
At any rate I think most healthy kids yearn to be adults and most healthy adults reminisce over being a child.
This is the human condition
It’s hard to explain.
It must be lived.