> I find this no less as unlikely as thinking humans would let wolves help themselves to their excess food

Wolves can extract nutrition from animal tissue which humans discard, such as bone and the tougher cartilage/connective tissue. Modern dogs still absolute love bones.

They also have much better night vision than humans, sense of smell and hearing.

So, follow human tribes and pick off the remains when they move camp. Maybe eventually escalate to sneaking in at night. The human tribes now become a "resource" which the wolves will start guarding from other predators, such as bears or competing wolf packs. The humans eventually catch on that the wolves are providing a benefit at very little cost - food remains which they are not eating anyway. They even start to share kills - the wolves being better at tracking game while the humans finish the kill with spear/bow.

When animal and crop domestication occurs, you get another benefit - protecting the flocks/herds/crops from marauders. Especially at night.