Not all. Most, certainly. But consider this: Humphrey Bogart as Sam Spade in The Maltese Falcon was a remake. There are a few other examples as well. While no classic, the Nicole Kidman/Alec Baldwin thriller Malice was an almost duplicate of a made for TV movie that was much, much worse.In my opinion all remakes fail. Some might come close or could be decent movies in their own right but they are never like the original.
Jeff Bridges did a decent job on True Grit but it definitely was not like the original. Even the script was not the same. Nobody could say “Fill Your Hands” like John Wayne did and Glen Campbell added some light humor to the film. Kim Darby was excellent.
And I sort of agree with the OP. Soylent Green wasn’t good, although it had potential, and an incredible cast. The problem, IMO is that it’s hard to shock anyone nowadays, and the cat is out of the bag on Soylent Green being people.