What you say is correct, of course.
But my point is genuine aliens will probably be a lot stranger than even the most skillful filmmaker will be able to conceive of. Bonestell was good, but he didn't even come close to the real thing when we actually went there and saw for ourselves.
When I saw the "alien autopsy" film I knew it was a fraud in the first 3 seconds. Now if the creature had looked like a cross between a tarantula and jellyfish, and designed by a biologist so it was biologically and evolutionarily plausible, I might have been tempted to fall for it.
As Mark Twain said, "Truth is stranger than fiction, because fiction has to make sense."
