Well, there's also first job, moving out to a rental and getting into a serious career (the hustling from job to job is a killer for anyone without nepotism on their side). You're right that there's cultural changes in the picture too, though.

Because they seem to be earlier to kids than millennials were, based on what I’ve heard,

It looks like average age of a new mother has gone up continuously at least in the US, actually. Teen moms are a big part of it, though, which brings up the the mean vs. median thing again.

Even if the data on housing is correct, are the non-homeowners closer or further from owning? The typical real wage has gone down, and I see little evidence that's concentrated towards older individuals like it would have to be to not hit gen Z. Anecdotally, in my family the last generation had an easier time. It's almost painful adjusting their old starting wages for inflation.