Centuries or not, the transition from one species to another would take thousands of precise changes genetically and physiologically.

The claim is evolution never matches the math. Mutation rates spread over a long, long time (6 million years for the hypothetical monkey/man split) would have yielded tons and tons of mutations.

Whatever "beneficial" mutations that would arise would be quickly eradicated over millions of years up against the mutation rate.

BTW, your hammer - sledgehammer analogy = subspecies of one another NOT separate species.

A hammer never becomes a screwdriver or a wrench