Hard working average kid? Sure. Maybe people underestimate how much work in this case.
Not hard working with genes like Carlsen? Sure. Maybe people overestimate how much work in this case.
Carlsen himself is not too proud about his genes but of course you know better...
And of course Ziryab's claim A lot of what people recognize as talent turns out to be a consequence of hard work is 100% correct.
In the first place, remembering 10000 games perfectly is some exceptional talent, ...
I don't think that he said he remembers them perfectly, although many people seem to have taken his claim in that way.