The development of Mechanics

Mechanics is the name given to the study about motions of the objects from small to the large.

It is the branch of physics concerned with the behavior of the physical bodies and its’ subsequent effects when subjected to external influences (forces).

But what could be its need and how it developed?
Maybe,

When people started hunting they make several weapons to get their prey. Here they focused only on the motion of the weapons. They never bothered about the cause or why it behaves as they need only their prey to live.

So they focused on how to attack the target accurately. They started to think for a good way to attack without any failures because always there will not be many chances. Sometimes it might happen with only one arrow and one bird[or one animal]. There is only one chance of attacking the bird. If the chance is missed then humans will not get their prey and they will not win in the battle of survival.

To solve these kinds of situations, they developed the so called mechanics. And not only for these cases but also for other cases like wars and traveling and etc.

When we want to compare the fastness of anyone or anything, then we can conduct a race between them.  Decisions can be made from the results of the race. But it is not always possible to conduct a race between them if they are animals. 
For example,

If there held two races in various places then how will you compare the fastness of these two different runners? How can you tell which runner is fast and which runner is slow? And another example is the comparison between ancient and modern. How will you determine the fastest person in the world in all time history?

In these cases you are in trouble of comparisons of old and new. Here you can’t conduct a race between the ancient and the modern racer. Then you may have to go to time travel.

      But we don't know whether it is possible. 
There are so many cases.

How will you compare the fastness of the animals like lion, tiger and deer? We can’t conduct a race with them.
Here is another example..
When there is a war,

If you want to calculate the time needed for your opposite king to reach your palace from the border of your country in a horse, then how will you calculate that time? In this case you must have known about the time elapse because it is the time you had to ready your army for defending the attack.

And in a war if a soldier runs a horse at its maximum fastness then how much time it will need to that soldier to attack the enemy at specific distance from your country. When will he attack the opposite troops?

You may have seen many milestones in the highway which shows the length gap between two places. But we know that the length between those two milestones was not calculated by taking a centimeter or meter scale. And then how it is calculated? How will you calculate the length between two points which lies very far from each other?

Like many and many questions were raised in our real life. To answer all these questions what we need is, a simplest way to make a data or detailed information about the motion of objects.

 That is how we developed mechanics to study about the motions around us.  
This may be why people started to define many terms in kinematics. When they started to define scientific terms, they did it with great care because the definitions should fulfill all their needs in various kinds of situations with good precision and accuracy.

       Above all, maybe the first mechanical concept is the so called day to day term "Speed".