Our dogs' diversity can be traced back to the Stone Age

I read a book on the history of dogs https://www.goodreads.com/en/book/show/40180044-once-a-wolf

The only thing I remember is he said dogs may have stuck around humans because, like wolves today do with others predators, they could follow them around and scavenge off their successful hunts. But it was also possible the wolves/dogs just really liked snacking in between meals. Wolves are very capable at finding their own food but they enjoyed some meat & bones thrown to them in between their daily rounds. That's what crossed the line between scavenging on the outside and a closer relationship.

My pet theory is that humans captured wolf pups, possibly by dealing with parents first, and kept them around as pets. People love playing with tiger, bear, and wolf pups and keeping them as pets today.

It would take generations of breeding the tamest ones, with the behaviors you wanted, to get something like the beginnings of domesticated dogs.