Invalid analogy. Humans are observed to exist. "Intelligent designers" as postulated by ID advocates are not.
Invalid response. Many things that are very forcefully put forth by science as existing have never been observed. They are simply and very stubbornly insisted upon because they are necessary to uphold the materialist view of origins.
How many people have ever seen the Oort cloud? Name them, please.
For that matter, who has observed one type of animal spontaneously evolving into a more complex type of animal for no other reason than a change in environment?
Pop science these days is filled all kinds of things that have never been observed. I would say that this once foundational aspect of the scientific method has all but been disposed of.