(Sorry can't see who you were quoting so answering both).
No, it was multiple examples of the 'protodog' which started out as a wolf (again not the wolf we have today, a forerunner of that animal) that had a slightly less fearful, avoidant reaction to humans...
The more those animals appeared, and the less avoidant they were, the more likely they'd be spotted by humans, scavenging around the fringes of human settlements.
People would have spotted puppies with curious features - floppier ears, curly tail, perhaps patches of colour or different patterns (we know this due to Belyaevs fox experiments).
People are not that much different in many respects... its pretty easy to see how some humans would find the puppies that looked less wolfy, acted more friendly, rather attractive. Perhaps they saw these 'proto-dogs' killing rats or chasing scarier predators away from the human settlement (in order to maintain access to food, not to protect the humans of course).
That attraction would lead to someone looking after an orphaned puppy, lobbing spare food to them... and that is the start of selective breeding, in reality!
Those people would favour the cute puppies, they would feed and tolerate the nicer behaved protodogs.
And they would not feed, protect or favour, but drive away or kill those that were not pleasant, were snappy or risky to have around.
This, unknown to them of course, selected for more friendly animals whose behaviour was easy to understand, whose appearances were more attractive. So they got more of that and again as Belyaevs foxes show us now, the appearances of these protodogs would change pretty rapidly with even more cute features, and cute behaviour appearing.
I believe that this happened multiple times across various human settlements and early wolf populations - the protodogs being SO dependent on humans meant that any time a settlement died out due to disease or famine...so did the protodogs, due to the distances between human settlements.
So if this had only happened once... we wouldn't have dogs.