First, excuse for I am not a native English speaker.

I have been playing at city builders for more than 20 years now (yes I'm old) and I love Forest Village. The work you have done is amazing.

I assume this game, like other city builders, is based on a productivity loop: as you progress, your city becomes more efficient at producing things, so you can build the same quantity with less workers, so you can free up workers and assign them to producing other things.
These other things will help improve productivity even more, thus creating the loop.

I think this productivity loop is a great feature. It's a good game mechanic that makes you develop your city in an interesting way, constantly thinking about how to free up workers to build these more advanced things.

My suggestion would be to improve this productivity loop. The longer and more complex it is, the better the game will be.

I have two main suggestions and several minor improvements.

The main suggestions are:
1/ Use villagers' lifespan as an important productivity contributor.
A the start of the game, the villagers shall live no longer than 35 years.
Then, as you bring food diversity, clothes, health care, better heat production, the lifespan shall slowly increase to 80 years or more.
The productivity improvement comes from the fact that villagers, in a lifetime, will spend more time working for the same time spent as child and student.
This will have the advantage to make the health buildings useful. Today, they are only useful if you make a big mistake. However, you can developp an entire village without needing them at all. I suggest they should be useful even without plagues, in order to increase the lifespan of villagers. Villagers will regularly go there and use herbs to improve there health.

2/ This one is more complex to implement: make food perishable.
One thing with city builders is that you can overproduce food such as fresh fish, vegetables and meat and they are still there in your barns years after. The improvement will make things more realistic.
There shall be two kinds of food. Perishable and non-perishable.
At first, you can produce only perishable food (fish, meat, vegetables), and there will be lots of waste. Then, you get access to buildings that enable to turn perishable food into non-perishable food (such as smoking the fish, drying the meat with salt). This will reduce food waste and thus improve productivity.
Also, cereals would be non-perishable, re-enforcing the interest for windmills and bakeries.

Now the minor improvements:
1/ Some productivity improvement can happen too soon in a game. Basic tool production is optional. So are fishing docks. You can build fisherman's lodges almost from the start.
2/ Using coal for heat seems to be much less efficient (per worker involved) than using firewood. So the only reasonable thing to do is to forbid coal consumption and use coal only for tool production. Wouldn't be better that coal represent a producitivity boost over firewood ?
3/ I expected high calory food to greatly improve productivity by reducing the amount of raw food required to satisfy the population, thus allowing to reduce the enormous work force dedicated to fields and fishing docks.
But this did not really happen. I ended up having a very important number of workers in bakeries and windmills and without reduction in the fields.
4/ The number of workers required to produce a reasonable amount of material in mines and quarries seems way too high. At some point, all you workers are in the fields when temperature is above 0 and in the mines when below 0.
5/ The market is like a game fix for unbalanced productivity loop. If it's impossible to produce something because you are unable to free up workers, you can buy it instead and everything is fine. It's a bit like cheating. If everything was balanced, you could produce everything by yourself.
6/ Cows shall produce hides. This will diminish the need the hunters and free up some more workers.

Finally: what happens when the producitvity loop ends ?
Yes, the game is not infinite and the productivity loop will end.
When it does, I believe the player shall be left with an important number of free workers so that he can focus on re-organizing and embelishing his city with "useless" buildings that only look real good (stone walls, gardens, beautiful trees, etc...).
Do what civilzations do when they are a the top of their productivity: build something for the posterity (pyramids, cathedrals, hanged gardens, etc...).