If your child can write a sentence, (even if you have to help them a little), they can create a movie with Plotagon.
Plotagon app is available on Google Play. Monthly subscriptions start from $1.49. I believe this is Australian dollars.
Please check subscription rates for yourself.
Whilst I have had a positive experience of Plotagon, you should always check things out thoroughly yourself, especially if you are using Plotagon with children. I would encourage thorough supervision.
Yes I was a bit slack, hence the animals rampaging through the zoo, as described in a previous post when my son was using Zoo Tycoon.