beta
I think, the reason why they don't remember the arts is because his father shut himself off for years after the mc's mom died. Also the reason why they don't recognize the mc is because he was locked in the shed for 10 years and like when he was 5 smth he was pretty neglected, they also didn't introduce him to the murim so probably why they don't recognize him anymore and the arts. Only the old people who fought his father knew the arts, since they considered him a formidable person. (The demon sect also knew his father because he fought them and almost killed the leader i think?)