Spurious argument, and a bad analogy. A car accident is a car accident, and one does not all other cars suddenly suffer similar damage. To suppose that one human made an error necessarily entails all other humans suffering for it is inventive but nothing more.
Certainly the human lower spine is sub-optimal, as is the arrangement of the eye. The spine clearly evolved for upright walking. And don’t forget dangerous childbirths, sore feet and wisdom teeth. We gained a lot when we evolved to walk upright and grew a big brain, but at a cost.
Walking upright freed up our hands for tool use, a key factor in human success, but this created tresses from gravity on the spine that frequently lead to unique back pains. According to anthropologist/anatomist Bruce Latimore at Case Western Reserve U. "we're the only mammals that spontaneously fracture vertebra." And the fact that the spine developed curves to keep balanced while upright really does cause it to become stressed at certain points, resulting in conditions such as lordosis (swayed backs), kyphosis (hunch) and scoliosis (sideways curve).
Also, our walking gait causes a twisting motion that, after millions of twists over time, the discs between the vertebrae begin to wear out and break down, resulting in herniated discs.
Our bigger brain meant a significant change in the architecture of the braincase, and that meant that we lost room for wisdom teeth – resulting in a lot of pain for a lot of people. With modern dentistry, that’s pretty easy to fix, but before that, it could be awful.
And upright walking and that large brain case has also made childbirth a lot riskier for humans than any other primate (apes don’t have midwives and obstetricians – humans almost always need them). A lot of women (and their babies) have died during childbirth.
Yes, I'm fully aware of punctuated equilibrium or the other terms used to describe the fact that evolution seems to happen in spurts. A lot of that is because environment change happens in spurts, too. Volcanoes, tectonic shifts leading to earthquakes, rifts and mountains don't happen gradually. Therefore one wouldn't expect evolution to happen gradually in response to such changes, either.
But the clear fact remains that, whether gradually or jerkily, the fossil record does not yield up one species AND its ancestors in the very same stratum. This is always the case.
