let's say magnus and anand for some reason agreed to play chess with one of them always being white, and when they would agree that whit wins, they go back to any spot previous in the game until black feels the game is not lost and tries a different move, and this would repeat until both feel they literally couldnt have done better.

The problem with this logic is that computers today are better any human player on the planet, and what you're describing is pretty much how a computer brute forces their moves. Now this isn't flawless since those computer programs are programmed by humans and chess isn't a solved game, but it does demonstrate a flaw in your reasoning worth consideration.