Snark aside, we have massively more people alive today than in 1900 and yet the proportion of people that die in armed conflicts is— while horrific- barely noteworthy in most years around the dawn of the 20th century and not infrequently dwarfed by the body counts racked up in those days.

That's true if your definition of 'die in armed conflicts' is limited to 'the soldiers on the battlefield.' If you extend that definition a little to 'people who would not have died if there hadn't been an armed conflict' then you need to scale it up to about a million people a year today. That's just from 5 countries where it's been studied. Globally it's likely to be much more. There's some good information about it, from a credible source, here: https://costsofwar.watson.brown.edu/costs/human