How can these modern translations and related translations be compared and contrasted to the original passage of the stories in their original bardic traditions?

Cross reference the orality work of Milman Parry, et al.

Can we, like Shepherds, tell a merry Tale? Stephen Duck, The Thresher's Tale (poem)

There's a link here to shepherds and a bardic tradition. In some sense, shepherds have lots of time to kill during the day and thus potentially tell stories. But they're also moving around their environment which also makes it easier for them to have used songline-like methods for attaching their memories to their environment.

How far back might this tradition go in our literate culture?

I also wonder at the influence of time on oral traditions as the result of this. Lynne Kelly describes calendrical devices in a variety of indigenous settings in Knowledge and Power in Prehistoric Societies for potential use in annual spaced repetition. What about the spaced repetition within daily cycles of regular work as described in this paper with respect to shepherds, fishing communities, and crofting?

The daily cycle of life may have been a part of the spaced repetition for memory.

How might we show this?

A quick example that comes to mind is the French children's song Alouette, Gentille Alouette which details how one kills, cleans, and dresses a chicken for cooking.