No Zapp, there is no such thing as a zero hour pilot. And no pilot (who has just finished flight school) suddenly becomes a captain of a 777, 747 etc.
There are many many many pilots in CX right now that joined with under 1000 hours, and all those hours were in light single engine aircraft eg. instructors. and they're doing great.
BOAC used to hire pilots straight from flight school, circuits & bumps in their large twin jets back in the day.
The problem now a days is with very senior captains and those who have retired, they joined airlines around the world with very low hours, sometimes no twin time at all, let alone a jet. Then years later when they were on selection boards they kept raising the entry levels to youngsters (who were like them) oh you need 1500 hours, then 3000 hours, then jet time, then EFIS time, then a degree! Meanwhile they had none of that when they joined. But when the world is short of pilots, they quickly change their tune.
Anyone can be anything they want, just put the work in.