As we have seen in Mahayana, our original purity (the Buddha-nature in each of us) is polluted by attachment or craving, which creates karma and rebirth.
Our originally pure nature (human nature) is the same as Buddha-nature.
In Tantric Buddhist practice, one tries to restore one’s consciousness to that original pure state of Buddha-nature. When we have done so, then we become a bodhisattva and help others.