This song was published in the late 19th century by an Australian called GH Clutsam variously through Boosey and others, and was written in the customary mock pidgin script of the time ("Ma curly Headed Babby").
However misguided it may look now it was glorified and owned as an anthem by Paul Robeson in his renditions, which are various.
The lullaby transcends the implications in the lyrics, and in my view can be sung without any concern of contempt.