Que Jay Garrick era um personagem cômico da Terra-2 ... não uma pessoa real na Earth-1 de Barry Allen.
Por Wikipedia
In 1956, DC Comics reinvented the Flash character, giving him a new costume, name, and background. Named Barry Allen, he was completely unrelated to Jay Garrick. In fact, Garrick never existed as far as the new books were concerned. Barry Allen's first appearance shows him reading a copy of Flash Comics, lamenting Garrick was "just a character some writer dreamed up".
Isso realmente é indicado no mesmo link ComicVine:
He [Barry Allen] also had a love of comic books, his favorite hero being the Flash ( Jay Garrick).
Eventualmente:
In 1985, DC Comics merged all of its fictional characters into a single shared universe. Jay Garrick now shared the same world as the new Flash.
Então, em resposta à sua pergunta, eles realmente não existiam na variante do mesmo universo / Terra até muito depois que o Flash de Barry Allen foi criado.
Você pode ler sobre o "status" atual de Jay no link do Wikepdia.