How did people come into existence?
We know that our parents brought us into existence; we know that our grandparents brought our parents into existence; and we know that we can continue to trace our ancestors back through our great grandparents, to our great great grandparents, etc. But where did this all start? If we could trace our ancestors back to the very beginning, how did the human race come into existence? Let me answer that with a story.
Once upon a time a doctor visited an engineer to get a tour of the engineer's new house. As they toured the house, the engineer pointed out how he could control every window, every curtain, every blind, every light, every door, and every lock with an app on his smart phone. This allowed the engineer to sit in his recliner and open and close curtains depending on the angle of the sun, open and close windows depending on the temperature and the breeze, and turn lights on and off depending on the time of day. After the tour was over and the doctor had taken in the beauty of the house and the convenience of the electronic controls, the doctor looked at the engineer and asked, "Who designed and built this house?"
Notice the doctor's question. The doctor asked "who". The doctor did not ask "what" caused the house to come into existence; the doctor asked "who" brought the house into existence.
The doctor asked "who" because when we see an object with a lot of pieces that work together, we conclude that an intelligent being designed and built that object. Whether it is a house, a car, a machine, or a computer, we know that intelligent beings designed and built those objects.
Now let's think about the systems that comprise the human body. There is the skeleton system, the muscle system, the nervous system, the digestive system, and the circulation system. There are organs like the brain, the heart, and the lungs. All these parts of the human body work together to enable people to run, walk, work, and play. And there is the reproductive system which allows humans to reproduce themselves.
Just as we look at a house and logically conclude that an intelligent being designed and created it, so too when we look at the human body, the most logical conclusion is that an intelligent being designed and created the human race.
Who is this intelligent being that created us? The term we use to refer to this intelligent being is the term God.