The answer is neither. The PM was actually Mission Control back on Earth. Their job was to support the astronauts who were actually risking their lives for the mission (okay building product isn’t that serious, but you get the point). As a PM, you cannot — absolutely cannot — forget that you accomplish everything through others.
Customer signals are the qualitative and quantitative data sets you accumulate on how customers are using the product. This data is the “ping” from the goal, and when you hear that ping get stronger, you know you aren’t veering too far off course.
One of the biggest issues I see with PMs is that they don’t take the time to really understand the goal. They may be able to recite the mission statement, but do they understand its foundations? I’m talking about the customer assumptions that led to it, the moral/ethical/design boundaries the company intends to stay within to achieve it, and the vision of the world’s future that it is supposed to live in.