I am new to the dialogflow, I want to know if there is any method that I can make my bot feels more human when the user interact with it? Many thanks.
Here is a good resource from Google. It talks about the Cooperation principle which helps you design helpful and straightforward prompts and responses for your users. It focuses heavily on principles that are used within day to day human interactions so you will get a bot that will respond according to the rules of human conversations. It is also closely related to dialogflow as it used actions on google as a platform.
If you want to know more about creating more human conversations I recommend you to look into human linguistic, but that is a whole new thing to learn and out of scope for StackOverflow.