To put the question in perspective, an chess analysis engine calculates each move till a particular depth to determine best move. How did humans, having a fraction of calculation power of a computer still managed to beat computers for a long time in the past?
Brute force for obvious reasons is not the optimum strategy for humans with limited mental capacity. So, humans study chess games, analyse positions and make general observations that hold true in majority of winning games. Principles like controlling centre, momentum, etc. These help in reducing the number of opening moves to a limited number of systems that do not lead to immediate disadvantage.
Further, note that initial positions have a greater number of best moves and as we go deeper into the game, number of moves that are best would eventually come down to one. To deal with this we created a body of knowledge like various systems (Sicilian, Ruy Lopez, french, nimzo indian). Then we make observations that hold true in majority of the winning games in a particular system. This leads us to general principles/strategies in that particular system. Like in queens gambit accepted playing as black, knight does not go to c6 in order to allow for the c5 pawn push. And such general guiding principles in each system.
Using these principles (to form strategy) and mixing it with intuition (pattern recognition etc.) and tactics (calculation), humans master chess.
I am an amateur only so correct me if I am wrong and missed something.
Further, Can we conclude that only way for a novice to get better (assuming he is already good at calculating tactics), only way is to improve his knowledge of chess (study more games and memorize observations specific to certain situations) ?