"Speciation is never observed."
Reply: This is not true. Do you know about squirrels on the north side of the Grand Canyon becoming different from those on the south side?
Evolution does explain why all mammals utilize the Krebs cycle, as Ichumenon has thoroughly posted. Evolution does explain why mammal fetuses undergo very similar development stages in utero. Evolution does explain why, for example, the cat family have unique characteristics (e.g., the retractable claw). Evolution does explain why apes and humans have similar blood types.
If an 'intelligent designer' with omnipotence used the same design over and over and over again, this is a poverty of imaginative design.
Evolution fits with understandings from astronomy, physics, chemistry, geology, archeology. It strains credulity that a book from 2000 years ago--involving a talking snake--has any truth that we humans don't have today.
I mean, snakes don't even pronounce Aramaic very well.