I totally agree with you, I was (actually still am?) young and have done a lot and struggled to overcome the very same thing you are.
I've worked (I actually did my initial CC training too) with 18 year olds, no-one is saying airlines don't hire people straight from school, it's just that they are careful when doing so.
Life Experience doesn't mean someone has travelled or what not, it's about the challenges and situations they've faced and how they've delt with them. It's about whether or not they can handle 100 passengers staring at them, looking for support and being able to control them when things go wrong. It's about being able to handle a angry passenger, a out of control child and still be able to smile and get the job done - because it happens every day.
Anyway, to be honest with you pprune probably isn't the best place to be researching... you'll find a lot of bitter people here, especially in D&G.If you want to research being a pilot seriously, goto your local flying club or school and do a TIF flight and chat to the CFI - they'll be able to give you some useful info.
If you want any info on being a pilot or FA you can PM me, i've seen both ends of the plane.
I just wanted you to realise that people work for many years to achieve their dream of working for an airline, it doesn't happen overnight. If you're serious about it and that's what you want then good luck to you, I'm sure you'll get there and remember that sometimes the journey is just as important as reaching your destination.