Disclaimer: my kids are mid-late teens.
I can't remember who I was before becoming a parent and that has never really mattered to me. I know I spent (wasted) a lot of time gaming, nothing worth crying over, for me.
Kids have to eat your life, otherwise you may not be parenting quite as much as you should be (this means a LOT of different things to everyone).
My brother and sister in law had kids about the same time as us, so we grew together as parents as the kids grew up together.
Friends come and go and the good ones come back again. Most of my friends have kids 5-10 years younger than mine and that means we're at different life stages - I can offer them advice as to what to expect and also sort of enjoy (and lament at the same time) that I'm passed the stage they're going through.
I actually took up a sport again when my first was a couple of years old because I wanted to normalise the playing of sport. This, I think, kept me with an outlet and some socialising outside of work and family. The more strings to your bow the better (I've recently been thinking about a concept I've made up called "distributed happiness", this feels like an element of that; as long as one of those things is doing ok, then your can hang your hat somewhere at least).
One more thing I just remembered: your childhood was for you parents, your childrens' childhoods are for you. Take their wonder and naiveté as your own and see the world as they do, but with the life experience and consciousness to know how important and mind blowingly amazing it all is.
I really miss my children's childhood. My aches and pains tell me I'm too old to go through it again, but I still wonder...
P.S. play your kids In The Hall of the Mountain King. My kids danced around like nutters as it built up and crescendoed. I've got a video of my daughter saying, in a sad voice, "ohhhww", after it finished. I also have some other music I played them, classical and complex but also simple to "hear" and they really responded to it.