Is the element barium helpful or harmful to humans?
The element of barium is invaluable to medicine. Barium is used for medical imaging of the human body to diagnose disease.
They are neither helpful nor harmful directly to humans, as they eat a lot of grass etc. farmers will class them as a nuisance as they compete with cattle and sheep for food. If they feel threatened they can be harmful. If you want to meet a kangaroo there are tame ones in zoos and wildlife parks, but you should stay away from wild kangaroos.