Sun Tzu is so fucking funny to me because for his time he was legitimately a brilliant tactician but a bunch of his insight is shit like "if you think you might lose, avoid doing that", "being outnumbered is bad generally", and "consider lying."
My personal favourite is his lengthy lecture on the subject of Supplies Being Very Important I Cannot Stress Enough The Importance Of Protecting Your Supply Lines But Also Supply Lines Are Expensive As Shit So Steal The Enemy’s Supplies At Every Opportunity.
One of the more important things to consider about any historical work is the audience it was published for. The Art Of War was aimed at fancy nobles high on philosophy with little practical military experience who were nonetheless leading armies.
Sun Tzu, after desperatly trying to explain extremely basic logic to a bunch of upper-class twits, basically sat down and wrote the most elaborate "As per my last email" ever