Time enters into the social decision-making matrix through the half-life of hoarding. After a period of time has elapsed a gift tips over from a good to a bad. The same is true for food. After a while it goes stale, and after a longer while it goes bad and becomes toxic. The same can be said for the vitality of people. After a while they lose their fertility and fecundity, and after a longer while they go bad and become ornery.
The passage of generations sets up a rhythm in the society. The tempo of tradita sets up a higher and a lower harmonic. Somewhere in there the interest rate gets set.
Conjecture: Interest rates get set in consideration of the circumstances of plenty rather than the circumstances of scarcity. Interest rates are about character, not consumption. The question is where does consumer debt fit it?