All creatures great and small

Physicists have a reputation for being the smartest scientists. Smarter than biologists. That's ironic since biology is far more varied and complicated than physics, so–if anything–you'd expect great biologists to be smarter than great physicists.

One of the putative evidences for evolution is the functional and structural similarity between otherwise diverse organisms, &c. Darwinians chalk this up to common descent. Mind you, that inference is tricky even on Darwinian assumptions inasmuch as Darwinians attribute some functional or structural similarities to convergent evolution rather than common ancestry. 

Anyway, they contend that if God really is the Creator, and more so if natural kinds originated in divine fiats of special creation, then we'd expect more diversity in how organisms are designed. 

But suppose, for the sake of argument, that God went back to the drawing board for each type of organism. In that case, the world would be far less comprehensible to man. The life sciences would be basically impossible.

Take a veterinarian. In a way, it's harder to be a vet than a doctor. That's because a vet must be competent to treat a variety of pets and farm animals, whereas a doctor only has to know about the human body. Human diseases. What is good or bad for humans, in terms of food, medicine, toxins, &c.

Even so, I imagine that in a pinch, a vet could operate on a human while a doctor could operate on a dog. If, however, every kind of organisms had a fundamentally different design, you couldn't be a vet. There'd be way too much to master. 

Likewise, you couldn't be a marine biologist if every marine species had a fundamentally different design. Admittedly, a marine biologist usually has a specialty, like dolphins or whatever. But a marine biologist is probably expected to know a lot about one (or maybe a few) species, and a little about a lot of species. Fish in general have a lot in common. That's what makes them fish. Marine mammals have a lot in common. 

But if God designed each type of organism from scratch, so as to share very few functional or structural similarities, then the natural world would be pretty incomprehensible to man. There'd be far too much to sort out. 

Or take something as "simple" and basic as yeasts. Essential to life. But imagine if every kind of yeast was radically dissimilar to every other type of yeast. Where would that leave us?

That, in turn, would make it basically impossible for man to adapt natural organisms to human use. Lacking any common frame of reference, it would be too complex to figure out.

It's beneficial to humans to live in a world that's understandable. That's something we can take advantage of. That's a sign of God's benevolence.