I’m not sure that it’s right to identify consciousness with Nirvana. Maybe some strains of Buddhist thought felt that Nirvana was not simply winking out of existence, that it was “somewhere” outside of the round of rebirth. In which case, the consciousness that “goes there” would be a special kind of consciousness, I suppose. We certainly see these sorts of ideas in early Mahayana texts, which assert that buddhas continue to “exist” in a noumenal sort of way, and that arhats actually become buddhas eventually. That sounds to me like a direct commentary on the concept of Nirvana, saying that it was not literally cessation but departure from existence.
On the other hand, it’s probably a little tone deaf to take those assertions literally. There was an effort to explain how buddhas arise and what their relationship to existence was. If their mission was Nirvana, why arise at all? And when no buddha exists in the world, why does a new one come to be? So, a noumenal buddha was conceived, which seems very Platonic to me. The noumenal buddha was a perfect form that doesn’t exist in the world but is the model for buddhas that do. Buddha nature is like that, too, but it’s immanent in sentient beings rather than being an otherworldly principle. But it still explains how buddhas arise.
I think the problem for early Buddhists was that they rejected the idea of a heaven where liberated people go like in other traditions. The afterlife became 100% not a place where liberation happens. But they did have a state of liberation that a person entered, which they didn’t want to be considered a place in another life. So, we find them talking about Nirvana as though it were a blissful place like a heaven, but they denied that it was when pressed on it. On the other hand, they also tried to tamp down talk of arhats ceasing to exist, too. It’s strange compared to other religious traditions.
Was this concept of Nirvana really the original one? I wonder sometimes. It sounds like it may have been a positive thing, and then it was changed to avoid the assertion. Jains have a heaven for liberated people, and Buddhists have the pure abodes, which is a heaven for the liberated-in-waiting. It kind points to something for me, but whatever it was, it’s lost to the mists of time.
When I read these various accounts on the topic that exist today, though, it seems that the problem for Buddhists revolved around trying avoid the absolutist logic that drove endless debates on the subject of the afterlife among other traditions. Buddhists didn’t exist in a cultural vacuum, after all. They had to deal with these other people who’d try to argue with them about this or that idea. Buddhists wanted to avoid getting wrapped up in an ideological mentality that leads to divisive arguments. So, there was a more practical reason for Nirvana becoming a blissful-yet-undefined sort of nihilistic form of liberation. IMHO, at least it was to exit stage right from the debate stage. So, then I wonder if they once had a positive view of Nirvana that they forgot after a long time trying to avoid arguing about it.
I think they often are describing similar experiences from different cultural and historical perspectives. And we all live in the same kind of world with other humans, so they discover similar answers to the same perennial problems if they are clear thinking. The ideologue will always claim their way is best, but really its another way in the world.