Why does the world exist? It just does, without a cause. Could it not have existed? Yes. Could it have existed in a primitive form, such that intelligent beings never came to be? Yes. So why does it indeed possess the property of birthing intelligent worlds? It just does, on its own, an absolutely random property, without which neither we nor these questions would exist.
As an option, a model of the universe could be as follows: it has a beginning, preceded by the Era of Nothing, it emerged with the spontaneous appearance of self-organizing matter and has since evolved. Its structure is a Multiverse or a collection of Multiverses, and its properties enable it to continue to develop and exist eternally. Indeed, at present this assumption, as a comprehensive view on the world's boundaries, lacks a complete and adequate explanation, but as a hypothesis, it warrants recognition, which can be designated by the term "beternism", from the words "beginning" and "eternity".
The existence of such a curious creature as humans suggests the existence of a Universe just like ours. And this doesn't mean it was planned this way or that this is the only possible mode of existence. Reality could have had other properties that would not allow for the emergence of any kind of intelligent beings. Yet, fortunately for us, reality is just as it is.
What do different currents of thought have to say about God and the universe? Theism — God created the world and manages all its events; Deism — God established the universe but doesn't interfere with it; Panentheism — God includes the eternal universe, and also exists above it; Pandeism — God, upon the creation of the world, became one with it, and is now the universe itself; Pantheism — the universe is equated to God, or is seen as sacred; Atheism — the absence of belief in anything supernatural, or the belief in the existence of nature only; Agnosticism — the answer is not yet known, or is entirely unfathomable.
The ultimate questions about our world: Why does it exist? In what way does it exist? Does it have a purpose? Could it have not existed at all? Could reality be such that no intelligent being would have appeared? Why does it have the ability to give birth to intelligence? Why is the world the way it is? Why is it so whimsical? What is its structure? Is it finite or infinite? Has it always existed or does it have a beginning? Does it have a prime cause? What lies beyond its limits? Is it eternally evolving or destined to decline in the future? Can intelligent beings live forever? Is the world knowable or not?
The origin of intelligence, is it a mandatory and 'inevitable' property of reality? No, it's causeless and spontaneous. Reality could have existed in a primitive form without the self-organizing property. So why does the Universe possess this property, thanks to which intelligence arose in the process of evolution? Just, without a cause. Without this property, no questioning being would have emerged.
Why does the world exist? The universe exists simply without a cause. It either emerged spontaneously or has eternally existed — that's a separate topic. Inherently, it possesses a self-organizing property but lacks a predetermined purpose. The universe is essentially a specific possibility for the birth and formation of various complex phenomena, including primitive intelligent life. Over time, these phenomena either get destroyed or cease to exist, while new ones may emerge. However, intelligent beings have the opportunity to extend their existence if they manage to harness the potential of their inherent qualities and the capabilities of their surrounding world. Fortunately, the potential of fundamental human traits and the opportunities offered by the physical world for flourishing are extraordinary, and it is our choice whether we reach the stars or regress into dissolution.