You assume that the engine has to get started at some point. We have seen basic building blocks being produced in nature. We know how these building blocks can

You assume that the engine has to get started at some point. We have seen basic building blocks being produced in nature. We know how these building blocks can be assembled in self-replicating molecules that we would not consider “alive”. The engine is always working everywhere, it is just chemistry. Now, there must have been specific conditions that lead to the production of some specific molecules, and we do not know all the details. These conditions are probably quite different from what we have on earth today, which does not help. There certainly is room for progress. But we do have a decent understanding of basic biochemistry.