I agree with the above comments and am delighted to see someone trying to bring in new players.
I personally feel I could get a group of my friends kids (of 11 up) and they'd have no problem playing the DARPG (Though the setting isn't exactly kid friendly...) and I've found that personally I don't have time to learn hugely comprehensive rule sets and as myself and our group ages we want simple, dynamic gameplay with plenty of RP opportunities. I feel like that's exactly what I'm getting here. Good god I remember trying to play Ars Magika when I was younger and my brain nearly melting out my ears.
As far as only releasing levels 1-5 first goes, honestly yeah my nose is a teensy bit out of joint but within the book you get a basic idea of how the characters progress anyway.
•Your character’s Health increases by 1d6 + Constitution.
• You may increase a single one of your character’s abilities by 1. If you gained an even numbered level, you must increase a primary ability. If you gained an odd numbered level, you must increase a secondary ability.
• You can pick one new ability focus. If you gained an even numbered level, you must choose a focus from one of your primary abilities. If you gained an odd numbered level, you must choose a focus from one of your secondary abilities.
•You gain the class powers for your new level.
Now that's every level for every class. Wanna go higher than 5? From reading the Rogue class you get a new talent or increase your talent at uneven numbered levels, and at even numbered ones you get a class specific ability (Stunt Bonus and Bluff for Rogue).
The only problems you run into is at even numbered levels and I'm sure there'll be plenty of suggestions here in this forum and ones that you can create yourself.
Personally I think that for the experienced player they have plenty of material to use if they want to go over level 5 within the 6 months, and for the inexperienced well I don't think many inexperienced or new players would get to level 5 that quick.