Mahayan was called Bodhisattva Yana or the vehicle of bodhisattva thus the way followed by bodhisattva. Later the term was generalized to the meaning the path and the teachings of bodhisattvas. (Nattier, Jan (2003),A few good men: the Bodhisattva path according to the Inquiry of Ugra : p. 174)
The idea of Mahayan goes to its basic in early Buddhism in India. Buddha taught the four basic truths and the way to attain nirvana. Later after his death he teaches bodhisattva the truth in form of lotus sutra. Disregarding the pessimistic nature of early Buddhism it states the worth of karma. (Kisimoto, Hideo Mahayana Buddhism and Japanese Thought, p.215-223)
The parable of burning house in the lotus sutra describes about riding the Mahayan. A father lives in a large house with a large number of children. When the father was outside, the house catches on fire. He looks up at the house; the children are playing unaware of the fire. The father looks up at the children and says: “Kids, come out of the house! All is burning!” The kids say: “Why? We are having such a great time here.” The father says, “I’ve got cards here for you to play with. If you come out of the house, you can play with these.” The children, excited by this, come running out of the house. They go to look for the cards the father offered them and then he says: “Well, it’s great that you’re outside, but I don’t have those cards. I’ve got an even greater card: a vehicle. So, hop on and take it for a ride”. Lotus sutra, Chapter 3 (the Hiyu Chapter)
The little cards that he first promised were those lesser vehicles that were preached before the coming of the Mahayana. They were meant to lure the people who were caught in the burning house of Samsara out, in order to receive the real teaching the Buddha has to offer them.
BUDDHA AND MAHAYAN
Mahayana teachings have always considered that the understanding of sunyata is an attainment which is extremely difficult and extraordinarily profound. For example, in the Prajna Sutra it says "That which is profound, has sunyata and non-attachment as its significance. Neither form nor deeds, neither rising nor falling, are its implications." Thus proposing the phrase ‘form is emptiness, emptiness is form’. But emptiness must not be understood as simple nihilism (the denial that anything exists), much less as referring to some absolute entity that underlies appearance. Rather, things are "empty" in the sense of lacking independent, persistent existence. (Francis Streng,Emptiness: A Study in Religious MeaningAbingdon Press, 1975)
This emptiness or coexistence exists even in the existence of Tathagata. About the existence of Tathagata Potthapada asks many questions from Tathagata. Tathagata declares that these questions are not answered by the exalted one. These questions do not lead one to live holy life. These do not take one to the goal or dhamma, aversion, higher knowledge, enlightened or nirvana. Thus the questions set on faulty premises like ‘Tathagata exists after death’ or ‘Tathagata doesn’t exist after death’ are not worth dwelling after. (Early Buddhist discourses, 140-142 John Joseph Holder)
Mahayana strongly depicts to the path of bodhisattva. These earliest Mah%u0101y%u0101na texts often depict strict adherence to the path of a bodhisattva, and engagement in the ascetic ideal of a monastic life in the wilderness, akin to the ideas expressed in theRhinoceros S%u016Btra. The old views of Mah%u0101y%u0101na as a separate lay-inspired and devotional sect are now largely dismissed as misguided and wrong on all counts. (Macmillan Encyclopedia of Buddhism(2004): p. 494)
Mahayan thus following the early Buddha teachings concerns the Buddha nature (Tathagata-garbha) of all living beings and their capacity to become Buddhas. This thought is present in all layers of Mahayan. Thus unless being certain creatures debarred from Buddhattva every living creature and animals alike have the seeds of Buddha nature within them and have capacity to become Buddha.