I wouldn't rely on a confidence as a stand-in for skill. Maybe it's cultural, but I don't trust people who are extremely confident during interviews. Interviews are stressful experience, people who come across as super confident[1] are suspicious.

On the other hand I'd hire a humble person based on this single trait alone and wouldn't regret most of the time. Humility is an exceptional marker for a good coworker. The best people I interviewed knew their limits and were eager to point them out.

[1] not overconfident, i.e. claiming to know more than they obviously do