Posted: Yesterday at 22:15
Bark will be an open invitation to cats to come and do their business and, if you buy a grade that's small enough to be comfy for your child, it will break down all too quickly and provide a great place for weeds to germinate and grow. Larger grades are not comfy to walk on for little feet.
I think the best option is to clear all the crud as you are doing - well done by the way - then level the soil that's left, rake it over and sow some grass seed in autumn or spring. There are various seed mixes available to suit different situations - shade, sun, hard wearing for children to play on or finer for a proper lawn.
It will need mowing every 5 to 7 days during the growing season but will be much easier to keep clean and tidy than bark and cheaper too than buying a membrane and then all the bark.
later on, as your child grows, you can easily add a swing or a wee trampoline as desired and then, when he or she has grown out of that phase, you can introduce plants and a seating area for mum and dad to enjoy.
Here's some advice on sowing a lawn from the RHS - https://www.rhs.org.uk/advice/profile?pid=424