From an evolutionary standpoint, the spine, it's literally not built to take the stresses of the body standing upright, there's a reason why apes use their arms to move as well as their legs.

The sciatic nerve routing. Going through the piriformis muscle was a bad idea.

Teeth, one set while we're a child, one set for 60/70 years.

The ear. Eyes have eyelids, you can close your mouth, but if there’s an extremely loud noise, your eardrum has to just take it and be irreversibly ruined.

The elbow. Why the f*ck is there a nerve that's so exposed, when you hit it at just the right spot it sends a jolt down your arm?!

Honestly, our appendixes try to kill us too often. something ain’t right with it

Knees are a good idea, but needed a bit more R&D before being rolled out.

Lower back

Would prefer it if my testicles had better armor

Achilles tendon. Single point of vulnerability that has no bone sheath and will absolutely cripple you if it's f*cked with.

Having sharpened rocks that slowly push their way through the sensitive gums of tiny humans who are too small to understand or explain the reason for their incessant crying. Bonus bad points for these tiny humans being designed to get 100% of their nutrition by latching their new razor teeth around the nipples of another human.

Ankles and knees. A woman can produce a whole new baby in 9 months but you twisted your ankle a little? Well, you'll pay for it for the next 50 years.

Bowels. I should be able to decide when to empty them completely! In one go and not a little bit now and more later!

Butt hair. Fun fact, if you shave it all off, you can't fart quietly anymore because your cheeks form a skin-to-skin seal.

A bony arse! It actually hurts to sit still

The male urethra. Idk who the hell thought it was a good idea to wrap the prostate around the urethra like a donut and then have it grow so you can’t pee when you get older, but someone f*cked up quality control with that one.

Ovaries & Uterus. WHY do they punish women with excruciating pain every month for not getting pregnant?

The air intake and fuel intake are the same system. That kind of oversight really chokes me up.

Sinuses. In all other apes (and most other animals), the drain is on the bottom. In humans, the drain is on top. That’s why we seem sick more often, our faces wait until 99% mucus capacity before starting to drain.

Eyes

Toes. So easily stubbed.

The laryngeal nerve. It’s supposed to connect from the brain to the larynx. Instead of just going down a bit, it goes down towards our heart, wraps around a major artery, and then heads back to about where it started. Because we evolved from fish the nerve was originally used to connect to the gills. That’s why it takes such an unnecessary detour.

Whose bright idea was it to put the clitoris outside the vagina?

Probably mouth, considering how so many people have messed up teeth as adults if they didn't wear braces as kids.

BOOBS! Why does a woman need to carry all that extra weight for the off chance she might have a baby in the future? What if she never has kids? Also, why all the different shapes and sizes? They're going to grow bigger when you have kids anyway, so why not make them all small to begin with? I feel bad for girls with massive t*ts. I can't imagine all that back pain.