There are so many claims about the origin of the American Bulldog, which one is true?

There has been a lot of controversy about the origin of the American Bulldog, a dog that is extremely similar in appearance to the English Bulldog of the 18th century, and with relatively few domestic breeders, we don’t know much about this dog. The first argument is that the early English bulldogs were brought to the American continent by some immigrants, and their initial role was to guard pastures, herd cattle and sheep, hunt, etc. After continuous breeding and reproduction, in order to adapt to the growth environment of the United States, the “American Bulldog” was bred. This explains why the American Bulldog is so similar to the “original English Bulldog”. It is the most popular expression in the eyes of many breeders and, of course, may be a sales tactic for the dogs. However, the American Bulldog can be found in contemporaneous paintings and sculptures, and people generally do not question this claim. 2. The second claim: Some people believe that the American Bulldog comes from a mix of different breeds because it has the characteristics of many breeds, and this claim is virtual because no one can say exactly what breeds are in its breeding program, so not many people recognize it. 3. 3. The third claim: This claim combines the first two claims, and proponents believe that the American Bulldog was indeed bred from the original English Bulldog by selection, but with a few more tidbits of story that appear closer to the truth. At that time, some settlers brought excellent bulldogs from the British Isles, Spain and Northern Europe to a new place. In the era of constant invasions, farmers needed to graze and protect their cattle and sheep, etc., so these bulldogs were trained to be a working breed, and the farmers improved its breeding to make the strong and agile characteristics of this dog more obvious. And because of the need for fighting, bulldogs were bred to be larger dogs that could easily fight cattle and hogs and had the ability to hunt wild animals, which is what we can now see as the American Bulldog.