The so called 'jungle music' is defined by the amen - it is not jungle unless it has it. Period. This Shy FX track cited in the article is "Original" because of the frantic MCing of UK Apache (what did this guy take in the studio!!). There's a whole lot of much more intense and better tracks. Try any Krinjah track like https://www.youtube.com/watch?v=ssPd9j6VaRw.
In fact, the label Metalheadz introduced the notion of dnb as a marketing move to distance its industrial-influenced sound from what was initially called jungle-tek, and was really techno with the amen break increasingly getting 'seasoned' on top of it. So dnb is not defined by the amen break, but rather by what is called the 'reese' sound and very specific arrangement and syncopation of layers of similar samples, which is nowhere to be found in jungle.
I presume there must be other reasons that mad amen got big - not only his sonic characteristics. In fact many funk records expose such loops, and lots of these had been used in pop music, not only underground. The sample itself, I presume should've been largely available during tracker times during 90s - I guess on BBSs or in sample packs.
We are also very familiar, thanks to Prodigy, with the breaks of Bernard Purdie (https://en.wikipedia.org/wiki/Bernard_Purdie) sampled at least twice (to my knowledge) by Liam Howlett for his biggest hist (I write his here because he is indeed the main producer of most if not all Prodigy bangers). But you see it was only Liam who sampled it, because he had the records. And I doubt hundreds of teen producers had the original Amen record. And I presume this has to do with the modtracker and trackers, because it was so easy to take s.o. else's samples and do stuff with it. It is not trivial to take samples from someone's MPC, though, so my guess is that Amen must be also regarded as an internet-age phenomenon, not purely musical.