The fundamental existential role of Space is as a container. It is in space that matter's residency is established and its adventures unfold. These adventures are composite of Pj Problems.
The first humans became aware that space is a container soon after they occupied space. They knew that they were in something bounded by the sky they saw above them and the earth upon which they stood. They knew that the something contained animals and trees that bore the fruits they ate. They also knew that the something contained streams and pond from which they could get water to quench their thirst. We do not know what they call this something (the word space came from their modern descendants). The existence of ancient humans was replete with Pj Problems, for example, we do know that they often trekked long distances in varied directions in search of animals and fruits which they needed for sustenance. Sometimes, their movements were largely caused by unfavorable weather conditions. Their nomadic experience improved their sense of direction and distance. It also provided them with information about dangerous routes. Their experience in procreation, hunting and food gathering improved their sense of quantity, grouping and interaction. The logistical problem of traveling with an increasingly large family size was simply solved by leaving most members of the family in a designated area while a few specific members (the hunters) undertook the long and oftentimes dangerous trek in search of food. This arrangement was so successful that it became the forerunner of small ancient communities.
A community, no matter its size, is perpetually confronted with Pj Problems (these problems are usually grouped as environmental problems, political problems, economical problems, social problems, etc). The survival and prosperity of the community depend on its ability to efficiently solve these problems. So it is not surprising that ancient humans inorder to survive and prosper, were able to eventually extract the concepts of quantity, direction and distance (QDD), all of which are expressions of Pj Problems, from their awareness and experience of the containership property of space. By so doing, they set the stage for the two greatest human inventions: counting and construction.
Ancient counting was simple. The materials to be counted were matched or associated with another material, the counter which successively represented an inceasing magnitude of the material being counted. A key characteristic of the counter was that it had to be manageable. So the fingers and simple materials such as small sticks and pebbles, were commonly used. For example, a person who wanted to indicate the number of cows in his possession would do so by counting his fingers and stopping when the number of fingers matched the number of cows in his possession. The toes were used for further representation when the fingers were not enough to represent the material being counted. Primitive counting evolved as ancient communities grew. Techniques such as grouping evolved and eventually number systems were developed and established.
What counting was to numbers, construction was to shapes. Like counting, construction evolved from ancient humans' awareness and experience of the containership property of space. Ancient humans cleared bushes to construct primitive paths for their treks. They constructed primitive weapons to hunt their prey. As their communities grew and became more developed, they constructed roads, homes, granaries, better weapons, etc. By about 3800 B.C, knowledge of construction had developed so as to allow the Sumerian civilization to build fishing boats and to invent the wooden wheel at about 3500 B.C.
Essentially, Space is a Container. Some spaces are empty and some are occupied.