Here's why:
* "Child" isn't a common nursery rhyme: There's no widely known nursery rhyme with the name "Child". It's possible you're thinking of a specific rhyme or a variation of a more familiar one.
* Public domain is complex: Works enter the public domain after their copyright expires. Copyright laws vary between countries and can be difficult to determine for older works.
To help figure out if your rhyme is in the public domain:
1. Do you know the full lyrics? If you can provide the complete lyrics, we might be able to identify the rhyme and its origin.
2. Do you have any information about its origins? Knowing where you heard it or any associated information might help determine its copyright status.
Please provide more details about the rhyme you're thinking of, and I'll do my best to help!