I don't want to sound cliche but I really do believe that there is no "perfect mould" that CX has in mind. I believe they evaluate candidates on a case-by-case basis and on individual merit (experiences, achievements, goals, interests...etc).
I say this because I know cadets who were selected when >30, but I also know people who went through the process successfully when they were 18. What's more, some of the cadets that I know have aviation degrees, whilst others have degrees in engineering, law, science and medicine....on top of that, some of the cadets have no flying experience at all, whilst others used to be flying instructors...
Therefore, I think that as selective as CX is, there is no such thing as an ideal candidate. I think as long as you meet their requirements, though there are many things they look for (attitude, personality, experience...etc), they will evaluate you on an individual basis.