Answer your own question using HE/SHE or HIM/HER.
With regard to your sentence:
Ask “Who was an uncivilized child?”
If the answer is She, use WHO.
If the answer is her, use WHOM.
HE/SHE — — — WHO
HIM/HER— — — WHOM
E.g HE baked the cake.
WHO baked the cake?
He baked the cake for HER.
For WHOM did he bake the cake?
I hope this helps.