you're not wrong, but that's not exactly what happened. Agriculture itself was mechanized by the industrial revolution, affordable tractors (tillers, farrowers, etc.) and harvesters. mechanized railroads put more perishable agricultural goods "closer" to urban areas, etc.
if you look at the growth industry before that, it was mercantilist overseas trade.
The theory is roughly that before the Black Plague, the population was stuck in Malthusian dynamics at the top of the logistic curve - population had expanded to the level that land could support.
The massive deaths allowed the remaining population to only farm the most productive land, leading to a massive surplus. The elite were able to capture that surplus and fund things like art, science, etc. Some of those scientists were able to create technology that led to further efficiency gains, so that technology could make the economy grow faster than population growth could catch up.
There are a ton of things that allowed that surplus to translate into technology and economic growth. But AFAIK the leading theory is that without the massive shock from population decline due to the bubonic plague, that surplus would have never existed to begin with, so how it was allocated would have been moot.
One of the many, many descriptions of this is here (many because this is the mainstream theory): https://cepr.org/voxeu/columns/black-death-and-industrialisa...
The first technology wasn't the steam engine, it was eating beef instead of just grain, and having cattle pull plows. We don't think of that as a huge technological revolution, but it was a dramatic efficiency gain at the time. It wasn't a new invention, but there wasn't enough surplus to deploy it widely before that.
https://www.cambridge.org/core/journals/journal-of-demograph...
Maybe you mean this one, Green Revolution.
... was not what produced the British Agricultural Revolution.
Dropping from 90% of the population being ~farmers to 80% of the population being farmers doubles the amount of time people can spend doing everything else including research, manufacturing, education etc.
In many ways it was equivalent to the drop from 51% being farmers all the way down to 2%. However, it wasn’t nearly as obvious because 90% farmers looks a lot like 80% of the population being farmers and the transition was relatively slow and unevenly distributed.
