All people are different. So, there will be some variations. However, there are some basics that all people need to survive.
First, the most important thing a person needs to survive is water. A person cannot live without water for very long. A good estimate from most health professionals is that a person cannot live without water for more than three days.
Second, a person needs food. Again according to most people medical folks a person cannot live more than three weeks without food. So, from this perspective, a person needs water and food as the bare essentials.
Third, there are environmental concerns. If the person is in a very cold place, that person will need shelter. A person may die in a day without the proper clothing and shelter. So, when we consider environmental concerns, there might be things more important than food or even water.
In short, food, water and shelter are the most basic ingredients for life.
Air is the first necessity for people to survive, as example the earth is the only planet that provide the air to us. that means people just can alive in this earth because the main necessity is provided by this earth.
Water is the second, humans need water because our body consist water the most.
Food is the third and the rest is all about the compliment of our physical need like clothes, good environment, family and etc.
That's according my opinion, it's nice to share with you guys =]