'Couldn't' is according to biology and its terminology, which changed the meaning of species and genus with the modern classification system.
Yes, it's called learning and making progress.
But you have already demonstrated on multiple occasions that you are somehwat allergic to progress and learning...
It's not really science's problem that you insist on continueing on with outdated information.
Prior to that they had both been referred to as (and meant) Created Kind (with variations) by nearly, if not all, bible interpreters
So?
Again, there is no evidence at all of a Created Kind evolving into another kind.
Here's another, likely in vain, attempt at asking the question: what EXACTLY do you mean by "kind" in the biological sense?
I'm looking for a definition that allows me to take any 2 organisms and objectively determine if they are the same "kind" or not.
Again, this is an honest plea: give me such a definition.
And really do your best - there WILL be a practical test of your definition. We will look at various organisms and see if the definition helps us in determining their "kind" and if others succeed in independently coming up with the same conclusion.
A definition of the word "kind" that does NOT allow us to identify if 2 random organisms are the same "kind" or not, is utterly useless and meaningless.
What is your definition of species?
From my layman's perspective, I understand that how a species is defined, might depend on the angle from which we are approaching this.
The most common definition seems to be "populations that interbreed".
Meaning that if you have population A and population B, they will be seens as different species if A and B does not naturally reproduce. So it could be that they CAN reproduce AND produce fertile off spring - but that they just don't it.
Another definition that is used at times, says "populations that
can interbreed and produce fertile off spring", but which don't necessarily interbreed in the wild.
I'm happy with either definition.
So, to conclude:
Population that
can't interbreed (and produce fertile off spring), are definatly different species.
Population that
can interbreed, but naturally don't, can also be seen as different species.