High heels were invented for men — soldiers, actually.

Around the 10th century, Persian cavalry soldiers wore heeled boots for a very practical reason: the heel locked the foot into the stirrup, keeping the rider stable enough to fire a bow at full gallop. Fashion had nothing to do with it. Survival did.
When Persian diplomats arrived at European courts in the late 16th century, the Western aristocracy took one look at those heels and decided they wanted in — not for the horses, but for the status. European noblemen adopted the style almost immediately, and the higher the heel, the higher the rank it signaled. King Louis XIV of France famously had his heels painted red to mark royal privilege.
Women began wearing heels in the early 17th century, initially as a way of borrowing masculine authority — the heel was a power symbol, and they knew it. Over the following century, men's heels gradually flattened as Enlightenment ideals pushed back against aristocratic excess. Women's heels stayed, and then grew.
By the 19th century, the origin in the saddle had been almost completely forgotten. The heel had completed one of history's quieter costume migrations: from a Central Asian battlefield tool to the defining silhouette of Western femininity — without ever changing its fundamental geometry.