1) How did Samson in The Holy Bible kill 1,000 Philistines with a jawbone of a donkey?
With the jawbone of a donkey.
(Is this a trick question?
It's like asking: how did the U.S. kill 35,000 people by dropping an atomic bomb on Nagasaki?)
https://live.staticflickr.com/1244/560246436_b1e91ba170_n.jpg
(And remember that at the time the typical person was much shorter than we are, though of course some of the Philistines were as tall as a very tall modern man...)
2) And how did Samson know he killed 1,000 Philistines?
Well...the Bible teaches us the following:
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He found a fresh jawbone of a donkey, so he reached out and took it and killed a thousand men with it. Then Samson said,“With the jawbone of a donkey,Heaps upon heaps,With the jawbone of a donkeyI have killed a thousand men.”
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It doesn't teach, "...and killed exactly a thousand men with it, no more and no less..."
So: the author was trusting his source
which may indirectly have been Samson himself.
The author didn't know the actual body count (to the man).
Samson most likely didn't know the actual body count.
The Philistines might have known the actual body count.
If we trust the Bible (for whatever reason)
then we trust the author
that 1,000 men (more or less) were killed
but we don't know the source of that number
and so we don't really know how reliable that number is.