I don't think consciousness is an is or isn’t. Something can be more or less conscious. Humans are quite conscious. Fish are probably also somewhat conscious, but less so than humans.

I'd say that an LLM perhaps represents something that would make a machine slightly more conscious.

The human brain also calculates a response based on some input, it's just a lot more complex.

If we build a machine that is as complex as the human brain, then yes, I would say that this is consciousness. The fact that we are able to explain how it works should not matter.

If a human is a 100 on the consciousness scale, an LLM (with memory) is perhaps a 4 or something. The interesting question is how far on the scale do you have to be to have certain rights etc. This is something that people are already discussing in regards to animals, i.e. a dog has more rights than an ant.