You cannot delete your GEDCOM and start over. All changes after it was imported will have to be done manually. There are several reasons that someone may not appear your GEDCOM.
Skipped means that they will be excludrd from the import.
People born before 11700 will automatically be skipped.
Additional GEDCOM imports will not automatically replace profiles created through previous imports. Duplicates need to be skipped during the GEDCompare process.
People without either a birthdate or a date of death will be skipped.
Decendants or ancestors of a selected person may be skipped.
People without names such as "Private" are skipped also.
Duplicates may be skipped.
It is possible that people without a bio or sources may be skipped.
Your GEDCOM will be reviewed by someone before being available. Someone more knowledgeable may think of more reasons your names ma not have been included in your download. I went over my last GEDCOM 4 times and still had people not included in the import.