Looking for a new job, I get job offers that are higher than what I have learned?

I trained as an office assistant (§66 BBiG/§42m HWO), left that in 2009, most recently as a security guard. Now I'm looking in the commercial sector again – problem. Whenever I apply, I get a barrage of rejections. Secondly, I get inquiries via job boards saying my profile would be a good fit – then the position turns out to be for claims adjuster – I'm not even trained that far, that would already be insurance salesman – and secondly, I don't have the confidence to do that at all – the exact opposite of applying and getting rejections, or then inquiries for higher-level positions that say I'd be suitable – I don't understand?