IGNORE=Y ignores only CREATE errors; for example, if your export file contains only one table, IMP un/pw FILE=file.dmp would first attempt to CREATE TABLE your_table and, second, insert data into it. If the table already exists, IMP will fail.
If you want to import data into an empty table, you'll have to remove records using, for example, TRUNCATE command (and include IGNORE=Y), or DROP the table.
Howevwer, not all is gloomy. If you specify IGNORE=Y and you are importing data that violates a primary key or unique index, the record will be ignored and your import will continue with an error message.
You do not need a parachute to skydive. You only need a parachute to skydive twice.