This was brought home for me when visiting Les Invalides, the French military museum (also where Napoleon’s and Marshall Foch’s crypts are at) several years ago.
I was looking at a French Old Guard Grenadier uniform on a mannequin. These guys were the premier heavy infantry of the European continent, the baddest of the bad.
I realized that I am considerably larger than the person who would have worn that uniform, or any of the uniforms there. Heck, my neighbor’s high school freshman (at the time) son was considerably larger. Now, he was on the HS football team, but still.
Modern nutrition matters.
I have a shooting replica of a Brown Bess. I'm 5'11" and it feels excessively long for me, even more unwieldy with a bayonet. I can't imagine being 6-12" shorter and hauling that thing around, much less fighting with it.
Imperial guard were big men for their time. The minimum height requirement was 5’10”; now about the average height of an American male.