[ZenGum]

As already noted, we have used our inventions to shield us from the effects of savage nature and our own individual defects. We have cleaned our water, defeated predators, immunised our young, worn glasses, used insulin, used IVF, and treated other diseases as they arose.
As a result, people who would otherwise have died before reproducing can now live and breed, and so our gene pool has become more varied and less "fit" in the sense of surviving without such support. Since we have such support, we are "fit" for our present environment.

While we have introduced a large number of new risk factors (obesity, corn sugar, tobacco) these generally don't bite until after you've had a chance to breed, so their selective impact is minimal.

Especially during WWI and WWII, we sent millions of our healthiest males off to die, and the physically imperfect were kept at home and are more likely to have bred. This would be outright disgenics (opposite of eugenics) but the numbers of deaths in those wars (say, 50 million total) isn't really that much in a world of billions.

Especially in the last 50 years, there has been more mixing of previously (relatively) isolated gene pools. Afro-Italian, Chinese-Hispanic, etc. I don't know if this makes much difference.

In the last 20 years, genetic counselling may have reduced the occurance of some genetic conditins, but only for the wealthy and I suspect the overall effect of this would be minimal.