Both cultures are Semitic and, generally speaking, all Semitic cultures share a common creation myth/story/legend – Each one tells it a bit differently from their culture’s point of view, so to speak, but essentially, they’re all the same underlying story.
These similarities are not at all uncommon (the flood narrative is another) and in fact, I think would be kind of very unusual if such similarities didn’t exist between narratives of this type.
Keep in mind too that these types of stories/myths/legends were passed on orally for who knows how long before they were ever committed to writing and not everyone committed them to writing all at the same time – someone had to do it first, so it may look like such-and-such culture/people had the story first, but it's more likely everyone had it at the same time; it may be that they were just the first to write the thing down.
Translations may not be complete insofar as the text may only be so long and either cuts the story off or only tells a small part of it, but the translations themselves are as accurate as possible. That said, as mentioned, there may be plenty of ‘interpretations’ of a particular story which embellishes it with things that were never in the original translation. Best to try and go with as literal a translation possible.
There’s plenty of ancient knowledge that has been lost through the ages. Then, just as now, people are quick to rely on the “latest and greatest” in technology and as we do so, these older ways of doing things get easily forgotten when modern technology is relied on. 'Modern', of course, being relative to the time one is discussing.
A quick case in point – I’d be surprised if anyone under the age of, I dare say even 30, really knows how to properly make use of a Library; back in the ‘dark ages’ before there were home computers/internet, you didn’t Google something, you went to the Library and did research. Another quick example of 'lost knowledge' - quick measurement of angles hold your hand out with your thumb directly pointing 'skyward' - the angles to each finger is approx. 90, 60, 45, and 30 degrees respectively. A handy quick reference that I'd be willing to bet was used quite frequently, but as we developed 'tools' and whatnot for measuring, these types of things passed into obsolescence and were soon forgotten.
The skies (astronomy) is another good one – at that time, once it got dark out, it was either a fire, lamp or candle – place yourself about a mile or so from the town, and it was pitch black; everywhere. The skies/starts, etc. would have appeared incredibly brighter than they’ll ever be in today’s modern world (unless you go to some incredibly remote region). They (the skies/astronomy) were much more easy to observe and study.
My point is that we may marvel and wonder how such a certain thing was accomplished when it ‘can’t be reproduced with ‘modern technology’, but I think that’s a very modern mindset of sorts; obviously ‘modern technology’ wasn’t needed – just good old fashioned know how that has long been forgotten.
