Is AI good for future human development?

This is a very big question.
In short, no, human brain will not 'decrease'.
Yes, AI is good for human development.

AI is another recent technology leap after the PC, the internet, and the mobile phone. This will significantly boost human productivity and worldwide GDP. However, this will widen the gap between countries that adapt to AI and those that don't, almost like living in parallel universes. This is because, currently, only a few countries and people realize AI's significant value. Some even claim that the next world order will be based on IT capability due to the enormous economic advantage. (The fictional drama "Silo" illustrates how significant IT can be in shaping society.)  

Secondly, the current generative models and LLMs are built on a self-attention structure, a fundamentally flawed approach to human language understanding. AI doesn't, and cannot, understand language the way humans do. Because of this, AI does not and cannot create, at least not in the same way humans can, by far. (You can also explore Yuval Noah Harari's ideas on AI for further insights.)

My suggestion is to just pop a few TED videos and you will know better the AI situation.
ps. can you differentiate which part of this reply is written by AI?

Currently, the usage of AI is a very serious and rampant issue in higher educational institutions.

Many students were already caught using AI (eg. chatgpt) entirely for their assignments and projects.

All these strawberry, spoon-feeding, instant gratification generation will be coming to workforce soon. They just want the easy way out to do things.

Another issue is that you can see for yourself from /k itself, there's an increase in the number of students enrolling in international schools.

The extremely very good students (those type that will end up in Oxbridge (Oxford, Cambridge, MIT, etc) are only few and far between. And then you have some who are least good in some way while the majority of the students in international schools are just hopeless, mostly coming from rich parents who don't discipline their kids at home in the first place.

As more ppl parents shifting their kids towards international private schools, this will also not be good for the workforce. It's all about spoonfeeding in those schools.

Just speak to teachers who are teaching there, not parents who will just exaggeratedly gloat how competent their kids are by attending those schools.

Chinese independent schools is like the last bastion to enforce discipline among students.