The origins of everything around us is pathetically not known in exhaustive detail, even to experts in geology, geophysics, archeology, anthropology, microbiology, and astronomy, as to specifics about precise timing along with intricate and timely mechanisms of construction regarding what is observable and detectable to human perception.
However, some basics have been discovered by scholarly research as to types of initial manifestation and sequential appearance of what is known to have existed and yet exists both on planet Earth and within the cosmos of the Universe.
Most scientists of repute agree that Earth is less than 9000 years old, verified by historical textual records plus proper understanding of radioactive dating methodology using non-arbitrary starting-point standards with allowance for radioisotope mixing of unknown extents, and that planet Earth came into existence alone with nothing else contained in the Universe.
The laughable theory of a childisly-named "Big Bang" exploding out pieces in every direction of hot matter at high-speed velocities into space far overwhelming any weak gravitational attraction between them, and then magically organizing themselves by themselves into detailed entities, is of course ridiculous absurdity.
Clearly, planet Earth did not have a will of its own, nor capacity by itself, to come into existence nor assemble itself in orderly detail, but the required supernatural source of it and entities relating to it coming into being is beyond the scope of this analysis, and speculation or declared knowledge of that would of necessity involve study in the science of theology.
For whatever cause, and by whatever physical means, it is known that Earth previously existed as a globular sphere completely covered by liquid water.
No land forms would have been visible at that time for two reasons:
(1) there was no light source existing at the time to illuminate the watery planet, and
(2) the entire surface of planet Earth was covered with water, and not lava nor anything else.
At a certain point in time, and without any luminary light source, what is known as time duration periods began, measuring the sequence of appearance of environmental inceptions that followed each other very quickly.
Scientific records reveal that one of the first phenomenon that happened was the appearance of a light which consequentially illuminated the watery planet Earth. Where the light originated from, its placement, and how is originated, is - up to now - not known.
What happened next was a separation all over the planet of water at two different levels, with a space between such. That is to say, a sky formed between the layer of planetary surface water below and the layer of what essentially was atmospheric water above.
In some texts, that sky is termed: "the firmament."
The next event which occurred very soon afterward was the appearing of land surfaces all over planet Earth. Whether such land rose up from inner-core lava magma eruption through some previously-restraining barrier within planet Earth, and/or surface water sank into storage crevices exposing that land area, is subject to speculation. Whatever the case, some scientific texts refer to that exposed ground as: "earth" - not be be confused with the same term Earth used to designated the entire planet itself.
Upon that dry land earth, reproductive vegetation of all sorts appeared all across planet Earth, which would not have been possible had the water on the planet not been segregated as previously described.
The new planetary vegetation required sunlight for photosynthetic growth, and it so happened that the Sun, moon, and stars of the solar system and beyond into outer space of the Universe came into being. Again, the mechanism by which that formation happened is not known at this time.
Being that vegetation was flourishing across the planetary surface, the appearance of sea life and flying creatures to feed on and supplement such vegetation happened, with the formation of animals and other land lifeforms coming into being and crucially interdependent with the growing plethora of other living organisms.
Research reveals that, in the case of land-based mammals and reptiles, earth (or: "ground") was the material out of which such originated, with the first male human similarly formed from dust of the ground. Thorough scientific investigation has indicated that the first female human originated out of part of the rib cage of the first male human. Again, the detailed mechanisms of all such formations are yet to be discovered.
It should be noted that the formation and appearance of all previously-mentioned phenomena obviously did not occur in pieces or in time-separated parts, because each entity mentioned had to be fully developed and fully functioning at once for each entity to survive and independently continue to exist.
And, again, the source of the entities formed and functioning in "adult" form right away involves study into the science of theology, which, as previously mentioned, is beyond the scope of this brief origins analysis.