And yet, the entire Theory of Evolution *depends* on ancient Fish having an immune system that no fish DNA on hand supports.
Pity...
The prokaryotes were doing just fine, until the Eukaryotes came along, with their ‘cell nucleus’.
These ‘advanced’ Eukaryotes then went about ‘evolving’ and are responsible for creating all the diversity of life that is and has been on Earth.
The prokaryotes have been protesting this for billions of years, fighting back, trying to destroy the Eukaryotes, but those darn Eukaryotes are pretty smart.
Prokaryotes: “We are not just a Virus!”
Eukaryotes: “You’re just jealous because you have no nucleus”
Will it never end????
If you mean a common ancestor of humans and modern fish, perhaps. But loss or modification of function is not code skipping.