Basically i am asking how scientists and smart people said the world became a thing, and how people who believed in greek/roman mythology said the world became a thing.
There is a lot of unpack here, not the least of which is setting aside the idea that there is a difference between "smart people" and those who believed in Greek and Roman mythology: every period has had its "smart people" and intelligent people in every period have concluded some things that could be ridiculed by subsequent times with "modern" perspectives.
So what you're really asking here, I suppose, is regarding the fundamental difference in worldviews based on belief systems inherited by means of an oral tradition and one based on scientific process of deduction, experimentation, and the successive building blocks of the scientific process.
One could argue that the worldviews of both camps were/are a bit irrational: while the stories people told about how the world and the universe began can seem irrational, there is also something irrational - or at least unfathomable - about the idea of a cosmic explosion occurring billions of years ago. The primal event - the Big Bang - is a tough concept the wrap one's head around, including as it does the idea that there was a sudden event - proceeded by what??? - and that this event occurred many eons ago, the number of which is unfathomably large.
One of the reasons some seek what they perceive to be as a simpler explanation of Genesis is that the primal event of God's creation occurred in a number of years ago that one can wrap one's arms around (tens of thousands of years ago is something that can be rationally imagined, while billions of years is in all practicality an irrational, unfathomable number). This makes the mythology of Genesis seem rational and fathomable.
There is no question that the origin of the universe based on the scientific process must be embraced by anyone who holds the intellectual process in high regard. That said, don't be so quick to dismiss the intellectual capacity of ancient people and what they may have concluded. Ancient philosophers often set aside the mythic stories as nothing more than entertaining ideas while they sought to imagine more rational answers to the fundamental question of the origin of things. But the way people have interacted with these ideas and have embraced one scenario as opposed to another are not that far removed from one another.