Why not both? Isn't it possible that it was his passionate, persistent curiosity that allowed him to get to the heart of problems, see what everyone else missed, etc?
If so, then his passionate, persistent curiousity should be counted as a special talent.
The fact is that not many people could have done what Einstein did. Whether it was genius or curiousity or stubbornness, the puzzle pieces were known to many people and he was the first to solve them.[1] For him to dismiss himself as having "no special talent" - that seems to be implying that just about anyone could have done it. It's a kind of modesty that we seem to reward, as a culture, but I dislike it. If Einstein had no special talent, then what of the people before him? Were they doing something wrong?
[1] I'm not sure how long the world had to produce an Einstein, before it produced Einstein. Perhaps there were only a few dozen people who saw the puzzle pieces before Einstein did. That still leaves him in the top tier, but perhaps not the top tier of the top tier.
