(Remember that British and American English have different rules for the use of the present perfect. The comments and the exercises here refer to correct grammar for British English. In American English, it is often considered acceptable to use the past simple in some of these examples.)
The past simple is used to talk about actions in the past that have finished. It talks about 'then' and definitely excludes 'now'.
The present perfect simple to look back on actions in the past from the present. It always includes 'now'.
These sentences are in the past with no connection to the present.
Now look at these same situations seen from the present.
We use time expressions like 'yesterday', 'ago', 'last year', 'in 1999' with the past simple.
We use time expressions like are 'ever', 'never', 'since' with the present perfect.
Typical time expressions used with the present perfect in British English but often used with the past simple in American English are 'already', 'just', 'yet'.
We can use the time phrase 'for' with both forms, but with different meanings.