A lot of things were created and popularized for very specific reasons, but could feasably have been convergently invented for other reasons. Any examples of this?

This is a wierd abstract thing that's hard to describee, so I am going to give you two examples from my world: Firearms and Fashion.

In the real world, cannons were invented first, folowed by personal firearms like muskets, rifles, pistols and so on. Starting in 12th century China (ish, there is speculation they existed even earlier) and spreading out from there, cannons were used as artillery, mostly for punching through walls, and ocasionally for disrupting enemy formations. Hand-caoons have existed almost as long, but true handheld firearms did not become popular untill advances in metalurgy made muskets economical in the 15th century.

In my world, it was the opposite. Dragons, though rare, are a part of the setting. They can fly, which makes melee weapons questionable, but their armor is too hard for normal arrows, and they are too maneuverable in the air to use cumbersome siege weapons. The first true dedicated dragon-killing weapon was a spear called, of course, the dragonslayer. It was a short, thick spear with, a head made of an untra-hard steel alloy invented for the specific purpose. If you attacked against the grain of he scales and threw your entire body weight behind it from a running start, you would sometimes be able to pierce the hide.

A variant of the spearhead alloy, combined with a liquid explosive used for mining and terraforming, led to the creation of the first effective long-ranged dragon-slaying weapons, firearms. The quirks of using a gel explosive instead of black powder also caused other developments to happen a head of schedule. So the people went from pseudo-muskets to cartridge rifles in a single generation for dragon-hunting, and only later invented larger artillery.

-----

Another example is from the fashion world.

IRL the first high-heeled shoes were riding-shoes for cavalry, designed to fit into the stirrups more securely, originating in 10th century Persia and radiating outward. Because cavalry were generaly drawn from the upper classes in many societies, it gradually bled through into formal-wear for the rich and those who wished to emulate them. Heels changing from masculine to gender-neutral to feminine was a gradual process driven by sociopolitical forces way to complex to get into here.

My world anachronistically has high-heeled shoes as womens-wear in a quasi-medieval setting. The reasons for this a weird and complex but...

Succubi and Incubi exist in this setting as an actual race, in the same way as elves or orcs, with their own semi-realistic culture, society, and biology. They mostly live in small 'hives' nearby but distinct from other races towns and cities. One of the quirks of their anatomy is that they are quasi-digitigrade, walking on the balls of their feet but having a horny-like 'heel'.

Human women started wearing high-heels in a deliberate attempt to emulate them. This practice originated among sex-workers and similar groups, but gradually percolated out over time, fully entering the mainstream when one queen wore them (both for sex appeal, and because she was short).

There are other similar practices of similar origin. Succubi and Incubi both also develop unique marks on their body, some at birth and as they age, most concentrated around the face, abdomen, and forarms, and humans of both sexes sometimes wear paint or get tattoos to emulate these when they want to seem appealing, though this is still a fringe practice. And the most common perfume varieties are deliberately made to emulate succubus pheromones, having an unmistakable 'rotting roses' smell and sometimes containing psychoactive chemicals. Actual succubi and incubi also sometimes give bottles of pheromones and vials of venom to humans as gifts.

Any similar interesting examples of cultural convergent evolution in your world

*I don't have a gender-neutral term for the whole species. Ideas?