I know this has probably been said a million times before, you probably hear it A LOT, I know I did, but when you have your own, it's different, and it totally is.
I am just introverted in general, I have social anxiety, and have never been much of a kid person to begin with. Most of my life I said I never wanted children, despite that, I still got broody and now have 2 children. I personally have no issue telling my kids things or talking to them, I did sort of "get over it" with mine, though I feel that is mainly because I know them, I gave birth to them, therefore I am comfortable with them, and personal comfort plays a big part in it all, but there are times where I draw blanks. Most of the time I have no idea what to say to other people, so I sure as heck don't know what to say to their kids!
Where I avoided children before, I now will say a little something, or at least am not as fearful as I once was. I'm not entirely sure it's something you get over fully though as it is a part of your personality. The other moms I've seen at parks or dropping their children off at DD's school always know what to say, they are imaginative, gentle with their words or voice, they play right into the child's game or idea, I'm jealous, but that's just not who I am as a person and a mom. I do my own thing, I do things differently from them and probably always will. I've felt bad about the way I parent because of it, I've doubted myself so much, and have even gone as far as to think awful things about myself, so for me the biggest thing that has come about in my parenting is accepting the way I do things differently from others, the pros that come along with it, and the positives that have steamed from doing things my way.
Also Molly, I am the EXACT same way when it comes to play. I do NOT like to play with my kids, I will basically do everything but! I've always felt horrible to say that because I've always felt like every mom except me played with their kids, so it's nice to know I'm not alone after all