It has nothing whatsoever to do with us knowing we're here, but with other people knowing we are who we say we are. It's a record of when and where we were born. Besides, a few generations down the road the only way they'll know where my family came from is going to be by looking at birth and death certificates.
The birth certificate is fairly new, really. We have it as "proof" of where we were born, and to whom. Some people have their birth certificates altered later in life. Another person might be added, or another name. First and foremost, NONE of us asked to have a birth certificate. You can't refuse them when you are born, as you can't even talk. And, your parents are told that you NEED one. If you do not want yours, take it to the local social security adminy, and give it to them. Don't be brainwashed by what you read on the internet. Next thing you know, you will be sending some scam artists $2000 for your "inheritance" of $2 million bucks, from someone you don't know. Nobody has "done" anything to me because I have a birth certificate or social security number. You sound brain washed by internet propaganda. Cut it out. Get OFF the internet and find out what REAL life is.