I think I'm definitely not the same person now as I was at 24, or even 29. The thing is, I wasn't the same person at 29 as I was at 24 either, and I doubt I'll be the same person at 40. In other words, the process of change and growth doesn't stop - ever. Probably that's the biggest lesson I learned in my 30s.
I think the biggest mistake many 30 and 40-somethings make is to fit everything into an overarching narrative of growth and maturation. "I was young and foolish then, now I'm older and wiser." Because the narrative doesn't actually stop - we are still young and foolish, hopefully - and trying to fit yourself to it just ensures that you remain stagnant at wherever you were at 30. Instead of a narrative of growth and experience, it's really one of adaptation, of recognizing progressively more subtle distinctions in the environment and changing yourself in response to them. And in that narrative, it makes sense to listen to everybody, even to young people, so you can pick out the parts of their experience that are new and unfamiliar to you.
The older you get the more your perception of time changes. I think this is part of the reason that there are so few 20-something leaders of huge companies. Partly it takes time to prove yourself to enough people to get a shot. Partly because it takes a long time to be patient enough to where you can be effective at the job.