Do you agree that any person can make his own blog and start blogging , even if that person still as Primary School pupil ?

You need not be an expert to blog, you just need an audience. You don't need hundreds of thousands of followers. Just a few people who treat you as a knowledgeable person at this level.

If he is a good writer, and has some good skills on social media and how to market his blog, I think any person can make his own blog if he has a story or some knowledge that he wants to share.