As I see it, your argument is a correct application of the Anthropic Principle. It is a habit of correcting for the base-rate fallacies that people should develop and apply more often.
You can only ask the question because you exist. So there may be no better answer than that you exist. If that is the case, your question won't have an answer. However unlikely every argument may indicate your existence should be, it is a fact. Highly unlikely things do happen, given enough opportunities. We should not decide what we observe is an illusion, or that it is all designed, or that it is all simulated just because all of it is highly unlikely to come together naturally.
You might ask "Why are all intelligent beings bipedal" and somehow come to the conclusion that bipedality is what caused intelligence. But it is far more likely that intelligence is really rare, but will eventually arise in some being, and that being, at least on this planet happened to have two legs for a completely unrelated reason.
But people do assert those things. And they are not convinced by this argument.
The problem is that such arguments about what is likely in infinite or undetermined situations are not as easy to support as their finite analogs, which can be supported by guessing a reasonable base rate and doing some math. So this principle raises good insights, and produces fragile arguments.
It is, after all, possible that bicamerality and the need for the two hemispheres of the human brain to communicate very explicitly in order to make peace with one another is what led to our being the first animals to have the level of communication needed to support conscious intelligence. We have two brains for much the reason we have two legs. So bipedalism may make intelligence more likely. The argument has been made, and it points at some data, which remains inconclusive.
Our counterargument based on a sense of what is "far more likely" does not give us any indication where to look for evidence to support it.