Depends on which place you are talking about. Manpower is a blessing but excess of anything is bad even if it is a good thing. Too much of it could make it bad. Having huge manpower but not being able to use it in every field will make it a weakness. In many countries, there aren't many opportunities. Thus the competition is high. The government is unable to provide its population with work. In cases like this, it will be a weakness for the economy.
On the other hand, if your country can provide you with good opportunities, overpopulation won't be a problem. Despite having competition, everyone will be able to contribute to the cause. That's how this will become a strength of the country's economy.
But if you want to talk about the whole world's economy, overpopulation helps a lot. Everyone alive needs to consume food. Poor, rich, middle class. All of us need food. So as we consume food daily, we are helping the economy.
Cheap labor is based on work experience and also certificates of expertise. The price of a job is cheap. because it does not require expertise to make policies and decisions. the thing that can be done to get to reduce the price of a job is to take advantage of technology.
if the workforce in question is related to the public, such as social services. it can not. It's different if the work in question is related to technology, it could be replaced with a machine. for example in agriculture. The country can make the concept of automatic irrigation for example.
What if, rather than racing to the bottom with the automation route, we invest in improving worker skills? Upskilling and reskilling might sound like jargon, but they're genuine solutions for the future. This would not only improve job quality but also reduce the dependency on unskilled labor.
As for the public workforce, you're right; robots can't replace empathy, understanding, and human connection. However, in sectors such as agriculture, though tech can help, we need to consider the social ramifications. Farmers losing their jobs en masse to machines - sounds like a dystopian novel, doesn't it?
I think that replacing everyone with robots or having many workers where everything needs to be automated is not rational. We need to find a balance between automation and employee development.
As for agriculture, I think this area is still poorly automated, if you look at the world average. I remembered an example of how in a country like Poland, which is quite strong in the agricultural sector, migrants still collect strawberries through hard manual labor and receive little pay. (I apologize to the residents of this country for such an example. I mention this without malicious intent.)