There’s no evidence that they were the bones of very small children — one of the problems uncovered when they were examined by forensics guys (1930s?) was that they were remains of individuals too old to have been the princes if they’d died during the reign of Richard III. Also, there was no scientific dating. Also, the find spot wasn’t all nice and neat, and other partial remains were ignored. It’s not unlikely that they were from a burial ground, and could well have been much older remains, perhaps Dark Ages, perhaps Roman, perhaps pre-Roman.
The problem also is if the bones in the urn were identified as the princes, it still doesn’t tell us who had them killed - or if they were indeed killed. We do know from the 1930s examination that the bones didn’t show anything unusual except disease of the jaw in one of them.
Thanks for the info. Truly am engrossed by this era of history. Also spend a lot of time reading about Custer at The Little Big Horn.