The concept of "Worlds" denotes the emanation of creative lifeforce from the Ein Sof or Godhead through progressive, innumerable tzimtzumim or concealments.
In addition to the functional role each world has in the process of creation, they also embody dimensions of consciousness within human experience.
The ten sefirot "attributes" and their associated twelve partzufim or "personas" reflect this light in the Four Worlds, as do more specific Divine manifestations.
In Lurianic Kabbalah, the partzufim interact dynamically, and sublime levels are clothed within lower existences, a concealed soul.
Consequently, as Kabbalah becomes more of a metaphysical study, the terms "higher" and "lower" are used as metaphors for being closer or further from Divine consciousness, revelation, and emanance.
The 16th-century systemisation of Kabbalah by Moses ben Jacob Cordovero brought the preceding interpretations and schools into their first complete rational synthesis.
Consequently, each world also psychologically represents a spiritual rung of ascent in human consciousness, as it approaches the Divine.
He could have chosen to bridge the infinite gap between the Ein Sof and our World by a leap of Divine decree.