I’ve found it fascinating that in recent years so many of my Young Earth Creationist friends have basically adopted Ken Ham’s proudly proclaimed hyper-evolution (as depicted in exhibits at the Creation Museum and Ark Encounter.) They are OK with the rapid development of all of the world’s cat family species (lions, tigers, house cats, leopards, etc.) from the original cat pairs on Noah’s Ark in just a few thousand years—as long as nobody uses the word “evolution” to describe it. Ironically, many of the same people who reject the Theory of Evolution by saying “there is zero evidence for evolution” are willing to accept Ham’s imaginary super-speed evolution without any evidence at all for his claims.
Of course, many of those people insist that such a phenomenon is “merely micro-evolution” and is restricted “within a kind”. And just as their imagined boundaries for their idea of “micro-evolution” has gotten wider, so has the definition of “kind” (now known as a baramin among many YECs) become much broader than what I recall from the early 1960’s. It is true that classifications like “cat kind” and “horse kind” have been around for a long time—and Ken Ham claims that a baramin is usually a taxonomic family just as Henry Morris did long before—yet today there is no hesitation to extend a single kind to all bacteria when making bombastic statements like “Yes, bacteria can evolve but the result is still just a bacteria.” (The “just a” argument comes up a lot today.)
One of my great frustrations that led me out of the YEC “creation science” movement was the predictable adjustment of terminology to the brink of the meaningless. Thus, as evidence mounted for evolution, the associated “kind” simple got broadened and the definition of micro-evolution got more ambiguous. (“Yes, Darwin’s finches changed over time but each of those types of birds was still just a finch.”)