I think the fact that we've created machines that reflect the image of our own minds does indeed make those machines a useful analogy.
To you point, we can use computers as an analogy to figure out what questions to ask about the human mind much the same way we can use a scale model of an aircraft to investigate certain flight characteristics of the full-size model.
The important thing is to remember which direction the analogy proceeds. Computers are like our minds, more so than our minds are like computers.
