I think its central teachings is the Unity of everything
See:the basis of Hinduism is the belief in the unity of everything.
Jainism is originated from Hinduism. But their teachings are quite different.
Teachings of Lord Brahma or brahman is the base of Hinduism. Lord brahma taught first man Philosophy of life and way of living, it is now known as Hinduism.
Hinduism,
to not hurt
no. Hinduism is polytheistic, Christianity is monotheistic.
Karma, Dharma and Samsara
tae ni hudas..
Siddhartha Gautama never wrote down his teachings.
Hinduism is not based on any man's teaching. Rather it is based on teaching of Supreme God himself.
That is how I see it too since Gautama Buddha was a Hindu prince. The teachings in Buddhism is parallel to the Hinduism.
Out of many most important teachings are peace, One supreme god, help those in need. Always do good,Respect everyone, Nonviolence.
There are many types of Hinduism, avaita vedanta for example. There are many schools with different teachings. There is also Wisdom Christianity, which is a religion which is a mix of Hinduism and Christianity.