One possible interpretation is a person who has no sense of the continuity of mankind. No knowledge of history. Such a person would be generously called “uneducated”.

Yet another interpretation is that you seek a word which denotes a fixation with the present as “egocentric” denotes fixation with oneself. I flunked.

Could be Alzheimer’s if it’s a disease.

Could also be dementia, often a forgetfulness experienced by the eldery. It comes and goes.

Or just forgetfulness.

Absent-minded.

Dreamy.

And I’m sure a thesaurus somewhere has already printed out a long list for you… sometimes I don’t know why I try.

senile

amnesiac

oblivious

-MM