It doesn't change the fact that Iron was among the earliest minerals ever mined. And that
the oldest known mine in the world is also an iron mine.
Also, it is a major dislocation that Ancient Era has an improvement (mine) being unlocked before the resource reveal. Every other resource in Ancient Era is revealed either before or at the same time that the improvement is unlocked. Iron is the exception, and it comes at the expense of making Mining an aberration compared to all other first column Ancient Era techs.
Pottery, Trapping, The Wheel and Animal Husbandry already have similar effects. Mining is the odd one that doesn't have an immediate boost. Moreover, we can argue that, if unlocking Iron was that powerful, then Mining into Bronze Working would already outclass other tech choices in this era. Nothing prevents you from researching the current Bronze Working as your second or third tech and sell the Iron you won't be using for a whole era; yet, the discussion here has been that Bronze Working is weak, implying that an early Iron unlock isn't gamebreaking.
Which I disagree. Spearman having 50% higher base CS matters a lot, especially when going Authority. A Warrior benefits little from any combat modifier you add to it, and trying to compensate the lower CS with more of them means more maintenance costs. I always find Spearman noticeably more efficient vs barbarians, both in combat and in gold expenditure. This is especially true in starts with heavy rough terrain, where the defensive CS multipliers make Spearman outclass Warriors handily.
To me, the bottom tech is Fishing. Bronze Working is a solid tech to defend yourself from both barbarians and aggressive neighbors, it has a decent wonder for militaristic civs (and war is still the best way to win vs the AI), and it leads to Iron Working for the so desired Barracks-Forge-Arena combo. Even without the combo, merely having a Forge in a city with Iron tiles around is very powerful; you get science from Iron mines and Forge, plenty of production and at least one solid city for military unit production.