An ancient tribe of white folk hunting kangaroo? I must say as an Australian I find that very unlikely. Not to mention "Nobody knows..." song.
Just a tad racist this episode, perhaps?

Perhaps a little a-historical and churchy as well, but why expect otherwise considering the source.

Can a man outrun a kangaroo?

on how sick the kangaroo is I suppose. The Indigenous Australians used spears often with stick devices to propel them further and faster. I suspect that was much more efficient than trying to run the kangaroo down