Heck, in that case, you may as well just get a list of all the Oscar nominees for best original screenplay and start from there.
Even at that, Yojimbo was not the first movie based on Red Harvest. Roadhouse Nights came out a year after Hammett’s novel was published and was ‘loosely’ based on it, IMDb says. Must be pretty loose as the ‘hero’ has a name. In the book, he was referred to only as the Continental Op, that is, an operative for the Continental Detective Agency which was in turn, loosely based on the Pinkerton agency for which Hammett had worked for a short period.
DD
The Most dangerous Game has been re-made several times, recently with Jean-Claude Van-Damme.
(Yes, it’s based on a short story but I love to have an excuse to mention one of my favorite movies)
If you enjoyed the remake The Magnificant Seven you’ll be interested to know that Kurasawa’s other masterpiece The Hidden Fortress was remade by somebody and set in outer space… can’t quite remember the title though, 
Seriously, wow, your OP rules out “The War of the Worlds” too, dang.
and “Tarzan” and “Sherlock Holmes” and
…wait! What about ** Robin Hood**?
There have been many movies about Robin Hood, but they weren’t based on each other.
Regarding remakes of “The Magnificent Seven” – don’t forget Pixar’s A Bug’s Life.
As for remakes based on movies rather than on books, etc., I don’t know. I could make the case that an awful lot of the remakes of The Phantom of the Opera are real;y remakes of the 1943 Claude Reins movie, rather than of Gaston Leroux’s novel (or the 1925 Lon Chanet Version), since they have that plot element of the "wronged composer who gets disfigured> (the original Erik was born that way). So the 1962 Herbert Lom movie and the ca. 1974 “Phantom of the Paradise” and arguably some of the others fit your category.
It’s a bit of a stretch to call Three Amigos a remake of The Seven Samurai, at best it parodies elements of The Magnificent Seven but that’s all. Would you call Joe Dante’s Pirhana a remake of Jaws?
What about Galaxy Quest, which was obviously influenced by Three Amigos, does that mean Galaxy Quest is a science-fiction-comedy remake of The Seven Samurai, based on your definition?