How to pull a list of each unique number from sheet with many duplicates

I know I must be missing something super simple. I need to pull out a list of each unique ID number present in a sheet where many ID numbers are repeated multiple times across different columns and rows.

I’ve tried to use =unique a couple different ways on the entire table/sheet to pull out a list, but it doesn’t work. It returns results that reduce the number of IDs, but has duplicates and presents them in a table like format.

I just want a list of every ID that’s present, no duplicates.

Thank you