If the OP is talking real life, that's not an easy determination. Real life people don't have neat and tidy stats to mark dexterity and strength. That said, I'd say jumping far is more about strength than dexterity. Dexterity is more a marker of how coordinated you are with small tasks...things you do with your hand. agility is the more general term for a lot of the stuff we place under Dexterity in D&D which is part of the crux.
See, in D&D if the Strength stat applies to pretty much all types of strength and muscle development. In real life, a person might the equivalent of 14 Strength in one or two applications but not most of the others. And also note that 14 Strength is going to generally be the strongest person most people know. 15s+ tend to be uncommon and 18s are extremely rare. In any stat. Again correspondence to real world capabilities is fuzzy at best.
But yeah, Strength for distance, Agility for accuracy.
