If Magnus is not,necessarily, the best calculator or tactical player

how is he overall the best player in the world? what other aspects does he have that make him better than the others?

didnt you ask reddit already? intuition

Photographic memory while he studied chess books when he was younger(not necessarily openings), world class positional play and sense of strategy, endgame knowledge and strength

He is pretty good at playing good moves.

He's pretty good at everything, universal.

All that matters is good moves. (RJF)

ABC

calculation takes time, even if you are great at it...so you have to choose better lines to calculate to begin with. being able to calculate 40 moves ahead when playing the Bongcloud wont really get you far at the pro level.

also, I heard he is swell at not getting checkmated, and checkmating the other guy instead. seems like a good strategy.

He could be the best calculator.

Because of the ability of computers being able to solve chess better than any human anymore, the real theoretical best player possible would only have to be able to perfectly memorize every possibility the computer can make (or possible ones). So basically just remembering theory. When the game leaves theory that's when intuition and game sense takes over. Magnus has an insanely good memory and visualization skills, along with brilliant game sense.

There is no "remembering all of theory". There are billions of opening moves and billions of games to know and study. You don' learn by remembering, you learn by understanding positions and sharpening your skills of analysis. Skill isn't something you can learn from theory books, it's something you gain with time and dedication when you focus on assessment and analysis of positions. A chess games can go in some 10 to the power of 160 ways, even a cluster of supercomputers couldn't generate 32-man tablebases with the game being completely solved. Or if if they could, you'd be dead before they got the 5 % of the game.