How was the universe created?

The Big Bang event is a physical theory that describes how the universe expanded from an initial state of high density and temperature.[1] Various cosmological models of the Big Bang explain the evolution of the observable universe from the earliest known periods through its subsequent large-scale form.[2][3][4] These models offer a comprehensive explanation for a broad range of observed phenomena, including the abundance of light elements, the cosmic microwave background (CMB) radiation, and large-scale structure. The overall uniformity of the Universe, known as the flatness problem, is explained through cosmic inflation: a sudden and very rapid expansion of space during the earliest moments. However, physics currently lacks a widely accepted theory of quantum gravity that can successfully model the earliest conditions of the Big Bang.

We can't know for sure but a popular theory called the Big Bang suggests that the universe was created from an infinitesimally small point of infinite energy some four and a half billion years ago.