[nicephotog (OP)]

(It may be possible to commit immediate transcribe and layout of any manuscript to database or central db anywhere in the world and with generalist translation using utf-32 or 64 carrying a complete set of symbols , too, cross-reference people all the way from bc to present.
About the following , you may never after hours use the words "you still here?!" with the same meaning ever again!

Since between 200BC and 200AD the approximate total 60 million of WW2 was killed on the battlefields in ancient times, of people sitting there now in the 21st and 20th century doing programming or engineering , how many were light infantry heavy infantry and "skirmishers" actually trace to those foot soldier jobs whom survived or were survived (definitely) (and before muskets ... that effective point) ?

can prove such lineage by ancient records. AFAIK Ebla kept records of their (assault field) soldiers not merely the commanders.

Battles of Zama and Cannae are normal size 10 - 30 thousand per side of participants (usually 2 to 5 thousand death toll of the loser).
Fall of Carthage and battle of Kadesh are large death tolls of 50 thousand or more with over 100,000 participants.
However, around 1000 years apart, separately, the Chinese had two civil wars of Dy nasties that together almost total the death toll of WW2, their second war of this magnitude in the pair was in around 1200AD (one quoted as death toll 25 million, the other 35 million death toll).

Of anomaly, the battle of Wattling street with Boudicca?s uprising killed approximately 80,000 Roman and pro-Roman people while the final battle against the revolt army of Britain's killed 80,000 Britain's!

You could as much ask the statistical probability of such persons being descendant / directly descendant.

As a "bad" example to show what I mean, (prime minister) Winston Churchill was a "lancer cavalryman" took part in a direct conflict charge against Mardist Sudanese rebels!