But I would want to see some actual historical accounts or folktales of humans getting sidetracked by cute animals recently enough in our evolutionary history to matter.

Well dogs have been domesticated throughout history, as far as I know. So it seems to me that in the last 10 or 20k years there would have been decent opportunities for a lot of people to be distracted by cute puppies. Obviously before that there aren't any records.

But it seems to me that if humans interacted with other animals on a regular basis -- hunting, watering holes, etc., then it must have happened occasionally that they would interact with a baby animal from another species.

Perhaps the hunger instinct can be relied upon to steer one straight in such a situation.