You understand, don't you, that there are no -- zero, nada -- "entirely different species"?
All species share similar DNA and are more or less closely related.
Exactly how closely related depends on how you calculate the alleles, but typically it's said that humans & chimps are 96% the same, cats 90%, cows 80%, mice 75% and even fruit flys share 60% similar DNA as humans.
Point is, all life on Earth shares some similar functions and DNA, and is therefore somewhat related.
Nothing is "entirely different".
So man-made distinctions such as "breed", "sub-species", "species", "genus" & "family", etc., are simply efforts to provide rough ideas as to the degrees of separation between one population and another.
To pick one example, human "races" correspond to breeds in animals and varieties in plants.
All are genetically very closely related (99.9%) and readily interbreed.
Recently, DNA analysis of Neanderthal remains shows them to have been more distantly related than "race" or "breed", but certainly not a separate species.
So they are now classified as a sub-species of humans.
Among bears, for another example, Polar Bears were considered a separate genus from Brown Bears, until natural hybrids were found in the wild, proving they at least occasionally interbreed.
So today Polar & Brown Bears are classified as separate species in the same genus.
That's because scientists consider willingness and ability to successfully interbreed a strong dividing line between populations of the same species versus those of different species, genera & families, etc.
And the key point to grasp is that any two populations of the same species, if separated for long periods of time, will slowly, slowly grow apart genetically, eventually so much we don't classify them as the same species.
But where exactly such lines get drawn is a matter of definitions and conventions.
Psalms 73: "I believe the available evidence would point that these creatures have always been what they are, rather than in the process of becoming an entirely new species."
Studies of mutation rates in many different species show there are a few DNA changes in every generation, most harmless or harmful, seldom beneficial, but these mutations are prevented from degrading the entire genome by natural selection.
Natural selection favors those better adapted to their environments, so if two populations of the same species live in different environments, they will slowly adapt differently to the point of no longer being in the same category.
Occasionally though, speciation can happen relatively quickly, as the man-made speciation of wolves to dogs demonstrates.
"All species share similar DNA and are more or less closely related."
"similar DNA" is a relative term. That 10% DNA delta between cats and humans is a vast chasm, not a small divot.
The Bible speaks of God creating each thing: "according to its kind" - science can dispute this in theory, but not in fact - the DNA record confirms this at least in part, and it does in no way refute this view of creation.
I would posit that the term "similar" can also point to a common Creator.