In my opinion the central teachings can be found in the 9 points unifying Theravada and Mahyana
1. The Buddha is our only Master (teacher and guide)
2. We take refuge in the Buddha, the Dhamma and the Sangha (the Three Jewels)
3. We do not believe that this world is created and ruled by a God
4. We consider that the purpose of life is to develop compassion for all living beings without discrimination and to work for their good, happiness, and peace; and to develop wisdom (panna) leading to the realization of Ultimate Truth
5. We accept The Four Noble Truths, namely dukkha, the arising of dukkha, the cessation of dukkha, and the path leading to the cessation of duḥkha; and the law of cause and effect
6. All conditioned things (saṃskāra) are impermanent (anicca) and dukkha, and that all conditioned and unconditioned things are without self (anatta)
7. We accept the 37 factors of enlightenment as different aspects of the Path taught by the Buddha leading to Enlightenment.
8. There are three ways of attaining bodhi or Enlightenment: namely as a disciple (śrāvaka), as a pratyekabuddha and as a sammasambuddha (perfectly and fully enlightened Buddha). We accept it as the highest, noblest, and most heroic to follow the career of a Bodhisatta and to become a sammasambuddha in order to save others.
9. We admit that in different countries there are differences regarding Buddhist beliefs and practices. These external forms and expressions should not be confused with the essential teachings of the Buddha.
from Ven. Walpola Rahula, Ph.D.
And I would add to the above list (actually it is implied and mentioned in the teachings above) rebirth, not the rebirth of a permanent self or soul, but the transference of kammic energies. Without rebirth there would be sort of an instant "nibbana" or at least annihilation, at death, regardless of words, deeds, actions, during our lifetimes. Certainly not the teaching of the Buddha.