We cannot change the past. We can only take action in the present and, therefore, change the future.
Human beings intuitively divide time into the past, the present, and the future. We perceive the past as immutable and fixed, the present as reflecting actuality, and the future as undefined and nebulous. As time passes, the moment that was once was part of the present becomes part of the past; and a moment of the heretofore previously unrealized future arrives and becomes the new present. The past is a record, the present is real, and the future is an imaginary thought.
Do you know who your grand grand grand grand grand father is? Probably you don’t! If you want to know your very distant past, just look at yourself because you are the accumulated past, you are the ancient river coming from the valleys of the far past!