Earlier quoted context omitted.
No physical system is uniformly distributed, and dynamical systems ensure that it will stay that way, therefore enough differences are baked into the system that it's effectively impossible have equally functional systems everywhere. Some people can just lift more stuff than others, or think about numbers faster or whatever happens to need to be done and their labor is more valuable because it's more efficient. There…
Clearly their ability to lift is not why there are millions without clean drinking water, for example. You are right that there are difference built-in to humanity, but we have already overcome those with fairly common technology already. Now inequality is more about who your parents were instead of where you are born or other purely physical problems. We can ship drinking water to anyplace on the planet. We just are…
You make a great point here, and one I hope you continue to push for. Statements like Why must inequality be forever? will obscure this point as it doesn't include the nuance of "not perfect, just better". You will always find people who will argue that "Why must inequality be forever" is naïve at best, needlessly preventing you from finding solutions you might agree on.