"modern wolves are not dogs' direct ancestors"

This is an interesting experiment conducted in the USSR with foxes that seems to suggest that there were certain genetics that made certain canines within a species more apt to become tame. The foxes in the study were bred for tameness, the results were intruiging:

The domesticated foxes were more eager to hang out with humans, whimpered to attract attention, and sniffed and licked their caretakers. They wagged their tails when they were happy or excited. Further, their fear response to new people or objects was reduced, and they were more eager to explore new situations. Many of the domesticated foxes had floppy ears, short or curly tails, extended reproductive seasons, changes in fur coloration, and changes in the shape of their skulls, jaws, and teeth. They also lost their "musky fox smell."

So, seemingly, at some point, canines which tended to be more tame were attracted to humans, most likely for our garbage. At some point, humans took advantage of that tameness and started the domestication process, and further bred for tameness, which resulted in physiological changes.

It would seem that the dates for this process keep getting pushed further and further back, that dogs have been our companions for some time now.

I had an uncle that had an 80 acre farm in Ohio. He grew a variety of vegetables, had hogs, etc. I spent some time there in the 60s as a youth.
He had a pack of half wild, loose dogs. He trained them thru beatings and shooting offenders to not break into the chicken coops, which worked surprisingly well.
Dry food was sporadic, usually only in the winter. They competed with hogs for slop. I watched those dogs dig up potatoes in the garden and they would eat dry cow corn from around the silo. They also kept the rabbits and cat population in check.

Another study like this also found that at the time of domestication dogs had a genetic change which allowed them to digest starch (cooked grains).

The genomic signature of dog domestication reveals adaptation to a starch-rich diet

I'm not willing to say human scraps are more or less healthy than scavenging carrion or the weakest (possibly sick) animal in a herd. BTW offal has more nutrients than muscle meat.

I listened to that report on NPR. Interesting.
My thinking is that the wolves evolved into domesticated animals hanging around humans at first eating leftover carcasses then eventually as the got friendlier and closer,
Our scraps. Including fish parts, offal, rancid cooked food, whatever humans threw out.

You can also argue that might have not been the healthiest diet.

Although no pesticides, GMO or chemical preservatives.