I'm in my mid-50s. The generation older than me - my aunts and uncles - generally were in school until grade 8 and were out of the house and working by 16. My mother had her older sister as her teacher.

24 is not a child. You can vote drive, drive, drink, marry sign legal documents etc. And at least for women fertility begins to decline at 32. If you mean you will continue to grow as a person and develop new interests that hopefully never goes away. I went to grad school and was in academia for over a decade after my PhD. I have made two major shifts in my career since then. Old people still feel like they are in their twenties or early thirties mentally, we joke about it all the time. So congratulations, this is it.