We were born on the same day and in the same place. Birthday that we know is just a birthday of this body. Our body was born in each place and time. However, our consciousness has been born in more ancient times. It's that day, known as the Big Bang.
We slept until that day. We did not notice with our own existence. One day, we woke up abruptly. This awakened day is a birthday of our consciousness. For all the people, a birthday of this consciousness is the same day.
First, this awakened existence was alone. The existence of alone was split itself as a material. Its existence is even now just one. We feel others as a different existence, because the sense of people is divided.
We believe ourselves as the one of the seven billion people alive on the earth. However, all of the people were originally alone. Even people that we have never met, they are our own consciousness that awoke on the same day.
It is said that everyone are brother, but it is the same person rather than brothers. Even people who seem like a other people, it is starting from awakening of the same existence. Despite we are a different body, share the same consciousness even now.