Why has Ruy Lopez, a chess opening, been so popular for so long

Chess Openings: Ruy Lopez Ideas, Theory, and Attacking Plans - Remote Chess Academy

Ruy Lopez Complete Theory

The Modernized Ruy Lopez - Volume 1 - By Swiercz (paperback) : Target

The Ruy Lopez Revisited - Schachversand Niggemann

In this ruy lopez position, I played d5, kicking the knight away and trading LSB. Was this a good idea, and what plans should white proceed with afterwards? huge thanks in advance *

Chess Openings & How To Start Your Game Strong

VECO - The Ruy Lopez Arkhangelsk - IM Robert Ris - Volume 6

Chess Openings: Play Simply and Solidly as White in the Ruy Lopez with 6.d3 (The Martinez Variation) - HubPages

Anyone know why engines always suggest Ruy Lopez? Is that the best opening for white? : r/chess

Starting Position in the Ruy Lopez Chess Opening