Something like that happened to me. It's kinda like when you move out to live on your own, and then growing up real fast when you realize that if you leave something undone, the person who has to deal with it afterwards is you. Being the primary caregiver for a kid makes you grow up real fast.
Having a kid really drove home that a lot of things are up to me, because until a certain age, the kid's entirely reliant on the quality of your care. If you fuck up or miss something and the kid suffers, that's not the kid's fault - it's yours. The added burden or responsibility is huge, and you start to really check your behavior at a level you never had to before. No matter how much you want to do something or say something, you have to remember that the kid comes first, and that doing something just to make yourself feel better may not be what makes your kid feel better.
The emotional attachment is also something very different because having a kid is sort of putting your heart out there. It's emotional vulnerability in a way that you haven't experienced before. You love the kid, but the kid is so much more vulnerable than any of your loved ones. You can take care of yourself. Your friends, family and SO can probably all take care of themselves for the most part. But your kid? A young kid is way more vulnerable, and because you can only reasonably teach and protect your kid so much, that's scary.
That vulnerability is probably why a lot of media scenes surrounding parenting hit a lot harder to me now than before. Movies and such love to do shit like having a kid separated from their parents because of war or something, and until I had a kid, I just saw those things as just another movie scene. But now that I have a kid, it does hurt more to see those things because it's so easy to picture my own kid in those situations.