While writing an essay on "My Book" We write " I bought it from the market" Why don't we write " I have bought it from the market" or " I had bought it from the market"? Asked 1m ago
You could use any of the three. As is often the case, the choice of tenses in English does not depend solely on the events you are discussing, but also on how you are choosing to refer to them.
"I bought it from the market" is the most simple and obvious for this context. It says that you are choosing to regard the buying as complete. In an ordinary past-tense narrative, this is the most common choice, eg. "I bought it from the market. It was heavy in my pocket. I took it home".
"I have bought it from the market" is less common in this context, and implies that the buying is part of a continuing process that continues to the present. You might use this if you're telling the story in the present tense, for example "I've bought it from the market. It is heavy in my pocket. I take it home, and hide it." and so on. "I buy it from the market" would also be possible in this narrative, but would start the narrative with the buying, whereas "I have bought it from the market" would start the narrative just after the buying.
Use "I had bought it in the market" if the temporal focus of your narrative is in the past, but later than the buying, for example: "I took the book out to read it. I had bought it in the market that morning."