You may use a normal date-field and regarding the dates from today() - n as new and the elder ones as already existing and unchanged. It may not be perfect but will mostly serve the purpose - and it may only be the daily task and once a week/month in any idle hours a full-load is performed to fetch the neglected exceptions.
If lines can be added and modified (and even removed) then you can't create that in the script. Look at Qlik Talend Cloud and CDC technology to stream changes.
"My table lacks the requirements for incremental loading, how can I load incrementally?"
You can't, generally. You have to ask yourself (or your client) what logic can be used to recognize changes that need to be loaded, and how to recognize that the row in question needs to be changed, and if such a logic is available, that's your answer.
