Photography is an amazing form of expression. Not only for yourself, but through others as well. Through photography, you are able to capture moments in a specific time and (especially in this day and age), share that and have that moment be everlasting. Something great about photography is the endless amount of styles there are; photography can be generalized as just that one word but there is such a diversity to the way photos are taken. Take Terry Richardson for example; when you see one of his photos you can distinguish it so easily; his photos hold a certain style that is unique to him. Overall I love photography and always have; I take photos everyday and even though it’s just through my iPhone; I am expressing what I like or what I find interesting. It’s always the best feeling taking a photo that I think is cool or looks good, especially as I have a specific vision for photos I like.
Selfies aren’t totally my thing on the other hand. We’ve all taken them but it’s always hilarious watching people in public taking a billion pictures of themselves. Looking past this however; it’s an easy way to capture yourself and your look, along with your friends and family too. I feel it’s important to look at yourself and embrace/appreciate what you look like, and taking pictures of yourself is a good way to build up that appreciation; it can bring out confidence. If you like your outfit or your hair looks great on a day, take a picture!
I looked through Cindy Sherman’s Instagram and it’s kinda creepy, kinda tight. Through her photos it seems she is emphasizing that sometimes you shouldn’t take yourself too seriously! Especially on social media as a lot of times people take it way too serious. I respect Sherman for that; hopefully she inspires people to do the same; to be able to clown on yourself and still appreciate what you look like and who you are at the end of the day. 
Not taking oneself too seriously is an excellent way to interpret Cindy Sherman’s photos on instagram. I agree with you that they are certainly creepy, but you suggest, they are funny too, and it puts the whole idea of taking selfies in a more humorous light.