Hi, I'd be happy to test out your app.
I'm not withing your target age group (29!) but I do regularly test apps and games in this way. I have a couple of programmer friends who also ask me to beta test etc. as I love to play around and see whether I can break their apps.
I do happen to have a 4 year old nephew though, who I can also show the app too. He's very used to technology and plays with simple apps when his mother lets him. I'm seeing him this afternoon so could download and show it to him.
I can provide general feedback to you, and if the app is already published, would be happy to write a review via the app store also.
I look forward to hearing fro you.
ind regards,
David Brookes - UK