Why is it as Humans that we have not yet come up with a way to measure speed?

The old how long is a piece of string.

Think thread reminds me of another forum I was on years ago where a girl asked "Why is lava wet? Surely at that heat all the water would evaporate and it would turn solid"

OP, recalling my leaving cert & engineering physics, your initial query may not be as daft as it initially appears imho.

As there are actually many uncertainties in our 'known & observed' universe. (Whatever that actually is, since we are by definition observing that through the prisms of our own perceptions, constructs & the limits of these & our devices to measure such, etc, etc)

For instance, iirc, the dimensions of space & time & the effects of gravity & the like warp & change their fundamental characteristics as items that have mass such as matter, approach the speed of light. So hence phenomena like black holes, where even light appears to act like matter, & is governed by gravity etc, etc.

A rather bright German chap had a theory of relativity about all this kinda stuff that created quite a fuss back in the day.

Also is light made up of protons or waves!?! Answers via fibre optic comms only please ;)

And are electrons here or there? Iirc, if you actually locate one, you can't measure it's speed, wavelength or charge or something else about it. Pesky little sub atomic things those blooming elusive electrons!!!

So it turns out that our perception & measurement of things in our physical universe are not nearly as absolute, or universal, as many people seem to think.

Nonetheless the relative measurement of speed is fairly set in stone, excuse the pun, and particularly so if you unfortunately happen to run into such a stone at 80 m/s, knots, mph, or even little old leisurely kph. That would be pretty definitive imho....

Something mildly interesting brought to you by the mean value theorem:

If you travel a distance of 100 miles in one hour (going at any speeds you want on the way to make that journey in that time), you must have travelled at 100 mph at least once on the journey.

Not immediately obvious but interesting if you think about. The mean value theorem is one of the most important things in Calculus.

And the speedometer in your car is lying to you. You are not travelling as fast as it's telling you, that really annoys me.

Elon Musk agrees.

It measures air-speed. You need a GPS or ground bounce radar to measure velocity.

Gliders can have a relatively low cruising air-speed. It has been known for gliders in a strong wind to actually fly backwards in relation to the ground while maintaining their normal air-speed.