Basically everyone at the small company I work at has come up through the ranks. I've been there the longest at this point, and I started as a true greenhorn, with no experience, and I've learned on the fly for almost eight years now. I like to think I kind of know what I'm doing some of the time now ;-)
Our other employees that have stuck around and become productive have all been initially hired as part-time testers and interns. Some of them were students at the time, others were coming in from other trades entirely. But they all trained up incrementally on our products and learned our business over time. Granted, theres definitely been a filtering, as maybe a quarter of all those we put in those testing roles proved capable of moving on to doing development work, but that is much better than the success rate we have had trying to hire for actual development positions, whether junior or senior.
Our other employees that have stuck around and become productive have all been initially hired as part-time testers and interns. Some of them were students at the time, others were coming in from other trades entirely. But they all trained up incrementally on our products and learned our business over time. Granted, theres definitely been a filtering, as maybe a quarter of all those we put in those testing roles proved capable of moving on to doing development work, but that is much better than the success rate we have had trying to hire for actual development positions, whether junior or senior.