Yes grade school is useful, I must have forgotten to say HIGH SCHOOL HISTORY.
Of course civilizations are build on the shoulders of previous work. None of that has to do with high school history classes, which teach nothing useful. I at least learned some useful skills in high school and took mechanics, welding etc once I got that bs out of the way.
I'm saying finance, speaking classes, computer basics, relationship with peers and romance would be 1000x more useful than knowing who was the 34ths president, who invented electricity (who gives a crap, turning on a light switch is all you need to know and was lbd by every 2 year old on the planet alredy). Wars over tea... who cares? How is that preparing me for my first job interview or helping me decide what to do with my life?