

Well, the first step was making a machine that does every step of the process to make it easier. Then you combine those machines into one big machine, hence “combine”.
No one starts from zero and builds a machine like this. Each of those processes was its own problem that got solved first.


The first version is just a machine that mimics the human motion of doing that task. Its a mechanical reaper that is pulled by a horse:
https://okfronline.com/2024/02/inventions-of-agriculture-the-reaper/
Then someone figures out how to make a self contained engine and it becomes self propelled.
This is a process that occurred over centuries.