Who has not been mentioned as someone who actually invented the hamburger?

Here, Clint Murchison is the person who has not been mentioned as someone who actually invented the hamburger. It has been said however that his grandfather (Fletcher Davis) of Athens, Texas invented the hamburger in the 1880s.

And, according to White Castle, the ancestry of the hamburger can be traced to Hamburg, Germany, where it was invented by Otto Kuase. In 1891, Kuase created a sandwich made with a beef patty cooked in butter and topped with a fried egg. German sailors later brought the recipe to the United States, where the egg was dropped.

Next, Louis Lassen of Louis' Lunch, a small lunch wagon in New Haven, Connecticut, is said to have sold the first hamburger and steak sandwich in the U.S. in 1900.

Then, Charlie Nagreen is mentioned. He created the hamburger at age 15 when he served the first hamburger from a stand at the Outgamie County Fair in 1885.

Plus, there are at least 3 or 4 other serious claims. It is now hard to know who was really the first.