Why is the religious creation story unique?

There are Creation-stories all over the world; tens of them if not hundreds. This is because the Creation was a tradition going all the way back and shared by all mankind. As time passed, most of these stories became infiltrated by idolatry, with a phantasmagoria of warring deities. It is the Torah, in Genesis, which uniquely preserves the original.See also:

Is there evidence for Creation?

How many Creation-narratives are in Genesis?

The Torah states that it was written in its entirety by one author, Moses (Deuteronomy 31:24), to whom it was dictated by God (Exodus 24:12), including earlier events.
The Torah has one creation-narrative, which takes the form of a summary (Genesis ch.1) followed by an in-depth recap (Rashi commentary, Genesis 2:8).
When we see a newspaper whose opening headline is paraphrased in the detailed story, we don't ascribe the repetition to different writers.

But this kind of literary device, which the Torah employs to enrich its text, has been used by Bible-critics in an attempt to reassign and divide up its authorship.

The Jewish sages, based on ancient tradition, identified many of the literary devices used by the Torah, which include:

- recapping earlier brief passages to elucidate,

- employing different names of God to signify His various attributes,

- using apparent changes or redundancies to allude to additional unstated details,

- speaking in the vernacular that was current during each era,

and many more. While Judaism has always seen the Torah as an intricate tapestry that nonetheless had one Divine source, some modern authors such as Wellhausen (the father of modern Biblical-criticism, 1844-1918) have suggested artificially attributing the narrative to several unknown authors, despite the Torah's explicit statement as to its provenance (Exodus 24:12, Deuteronomy 31:24). This need not concern believers, since his claims have been debunked one by one, as archaeology and other disciplines have demonstrated the integrity of the Torah. No fragments have ever been found that would support his Documentary Hypothesis, which remains nothing more than an arbitrary claim:

Refuting the JEPD Documentary Hypothesis

The creation-narrative in Genesis (a Christian author)

The authorship of the Hebrew Bible