>>3829373
I'm NTA but it seems we're mostly on the same page. Of the attributes common in RPGs only STR, AGI, and SPD are objectively measurable and it's important to establish that as a first principle.
There may be overlaps (particularly at their peak) but that's a given because they're all measures of fitness.
>Speed
Movement speed as determined by biomechanics (body shape, leg length, height, etc.) but also aerobic efficiency which improves naturally over time when running.
>Agility
This covers the physical and mental reaction times, they're the same thing but traditionally AGI subsumes some of STR and INT takes the rest; what's left is some amalgamation of different unrelated things like eye-hand coordination which falls under dexterity but dexterity is a learned ability specific to some activity not a measurable quality common to all people.
>How do you quantify the "take a hit" portion of endurance
Throw END/CON and the health bar into the trash and put the non-health related parts like stamina under SPD, there's no one attribute that can determine a person's hit points so that part should definitely go.
>things like people who are generally tanky but have glass jaws?
In boxing that's down to poor technique and neglecting the neck muscles. If I were to gamify that it would be a weak spot on the head.