Is there any way that we can alter the voice of the google assistant into a particular human type voice? By using the audio clip of that particular person.
No, you cannot change the voice of the Assistant. The Assistant's voices are chosen by Google and meant to help the user distinguish they are talking to one of Google's voice agents.
Users can select which voice they want from one of several choices, but that is not something that you as a developer can control.
Conversations that use Actions on Google use the voice that is chosen by the Action's developer.