Specifically, one FIDE rated player was born before all other FIDE rated players. Who was it and when was he born?
I've no proof him to be the earliest born of them all, but after browsing the earliest FIDE rating lists, my candidate would be Esteban Canal:
Born in 1896, April the 19th, the Peruvian master was 75 when he entered the first published list in July 1971 with an Elo of 2270.
He beats grandmaster Friedrich Saemisch by five months.