This is definitely some part of it, but even then - quality also plays a role that we should not ignore.

The reason why we remember certain shows and movies from our childhoods is because they were actually great. The rest of the slop we watched has long since been forgotten.

Even comparing modern kids shows, there is a massive gulf in terms of quality (and honestly memorability) between Bluey and Peppa Pig, let alone the giant gaping chasm between those two and the Cocomelon-level slop being fed to them.