So you didn't read where I explained it's not so simplistic as you portray it? Do you understand that the genetic data that directly points to common ancestry is not simply "the sequences are similar, therefore the organisms are related"?
So overall, as it might need to be stated again, I believe in evolution. I merely think OP's reasoning is flawed in stating "Thing 1 is X% similar to Thing 2, therefore common ancestor".
I mention this 'cause I kinda get the vibe from your whole first reply to me that you may be under the assumption I'm against evolution or some nonsense like that.
And again, even with your addition of "shared genetic errors", it does
not become good evidence for the theory of evolution (and just because it needs to be said again, there's plenty of actually good evidence for that theory).
Because, again, "shared genetic errors" in copy/pasted genetic code would be something I'd expect to see in a genetic code written by a theoretical designer.
When I make a program that is very similar to another that already exists I may very well "copy" the existing program and modify it from there to fit whatever slightly-new function I need it to fill.
And if there was a defect I didn't originally catch in the original program, well then there is the same defect in the new one (assuming the defect didn't exist in a part that was changed).
Shared programmatic errors, if you will.
And yet these shared errors in the code, in themselves, do not in any way mean my two programs evolved from a common ancestor. No, both were designed.
And thus, I think it is
insufficient to claim that shared code, even shared errors, between two sets of code is evidence of evolution. Because I myself have encountered scenarios in my life where I came across common errors in code across two different sets of code, and yet I have absolute proof those specific things were
designed. These shared errors are
exactly what I'd expect to see from a theoretical designer copy/pasting some code, so the argument presented in the OP is a
bad one.
Likewise consider the very basics of gene editing that we have today. Usually, they copy one gene and add it to another species (usually plants). In those instances, the modified species could come to have shared genetic errors in common with another species that its ancestors did not have. (Kinda... I guess it depends on how you define "ancestry" in the case of GMOs... actually going forward, our understanding of "ancestry" is probably going to be radically altered by this technology...)
So if you want to say that shared genetic code, like OP, even accounting for shared genetic errors, is
alone sufficient evidence for evolution... well I can't agree. That's not a good argument for evolution, and since there are many good arguments that one could make for the subject, I don't get why anyone would want to resort to using it when there are a plethora of better arguments out there.
Again, that doesn't mean I think evolution itself is wrong, and I'm sorry if that doesn't need to be repeated as much as I repeat it but so often do people on this forum assume my position based on my criticism of an argument that I think it is requisite to keep repeating it.