You provided two great examples, the recurrent laryngeal nerve and vagus nerve as well as hiccups, eye colors, some anemias, like sickle-cell or iron deficiency are others. However, your misunderstanding about what evolutionary adaptation (or more accurately, natural selection) is doesn’t mean somebody else has to prove you wrong, just because you define something incorrectly.
And all I pointed out was that your description of evolution by natural selection was wrong, the natural selection process doesn’t care about the existence of things that don’t decrease reproductive fitness, so those features won’t be selected against. Things that may have been useful to an ancestor in a different body configuration but not us, may continue to exist, but that’s not an argument for its continued usefulness. So saying the fact a foreskin still exists therefore it must be useful isn’t supported by the way genetic evolution by natural selection works.
Sources aren’t even hard to find:
- “First, it’s important to recognize that not all of an organism’s features are due to adaptation. For instance, some non-adaptive, or even detrimental, gene variants may be on the same DNA strand as a beneficial variant. By hitching a ride on the same DNA strand as the useful variant, a non-adaptive gene can quickly spread throughout a population. In other words, just because a certain trait is there doesn’t necessarily mean it’s useful.” From: (https://www.science.org.au/curious/earth-environment/why-evolution-isnt-perfect)
- “But here’s where it gets interesting – some traits stick around even if they’re not particularly helpful. Why? Well, as long as a trait doesn’t actively harm an individual’s chances of survival and reproduction, it might just hang around in the genetic wardrobe.”
In fact, hiccups are a really good comparison. I’d say everyone has had or will have hiccups at least once in their normal lifespan. For some people they may even get stuck with them for an extended time to the point one seeks medical intervention.
But they are adaptation from an amphibian ancestor of ours that needed them to be able to transition from breathing in water to breathing on land, we don’t benefit from them anymore, but they don’t negatively impact reproductive fitness so they stick around. (See: Your Inner Fish by Neil Shubin)