One of the great things about being a parent is watching your kids grow into full-functioning, capable, independent humans.
The hard part is learning to live with the combination of swelling pride in the fact that you turned out some pretty good kids, and the abject gut-wrenching fear that you might have missed something, so you've basically set them up for something bad to happen because you're not around 24/7 to look out for them.
But that's mostly your ego kinda working against itself - and you have to let that go too.
In the end, I think every parent is - and has been - as good a parent as they're able to be at any give time.
As you grow older, you learn to watch more and more of the world go on without you.