Remember, we can use the present perfect or present perfect continuous to describe an activity that began in the past and that has continued until the present. For example:
a) I have had this car for ten months. (I still have the car.)
b) I have been living in Rome for six months. (I still live in Rome.)
And we use the past simple to describe actions from the past that we consider remote and with no connection to the present.
a) I had that car for four years. (I don’t have the car any more,)
b) I lived in Berlin for ten years. (I don’t live in Berlin any more.)
Compare these two sentences:
a) I have lived in Paris for two months.
b) I lived in Los Angeles for ten months.
In sentence “a” (with the present perfect) the speaker is referring to a situation that started in the past and has continued until the present. The speaker is still living there. And in sentence “b” (with the past simple) the speaker is referring to a situation in the past that has finished, and has no relation to the present.
Here are some more examples to compare:
a) l have worked here for six weeks. (I am still working here.)
b) I worked in that office for ten months. (I worked there in the past. I no longer work there.)
a) l have had this red jumper for three days. (I still have the red jumper.)
b) I had the blue jumper for nine months. (I don’t have the jumper any longer.)
Now, compare these two sentences:
a) John Grisham has written many books.
b) Charles Dickens wrote many books.
In sentence “a” we use the present perfect because the person (John Grisham) is a living author, and therefore the actions are recent and related to the present. And in sentence “b” we use the past simple because the author is dead, and therefore the actions are all in the past and perceived as complete, remote and with no connection to the present.