Not many people in Gaza today were alive in the 1960s. Citing history about what is going on right now isn't very useful. Both sides can point to historical events that make the other side wrong.
How is someone in Northern Gaza right now supposed to get to southern Gaza?
Also, Southern Gaza isn't safe from air strikes, so going there won't necessarily make them safe.
It is a cop out for Kirby to suggest that the reason there are people in Northern Gaza is because Hamas is using them as human shields. Hamas might be counting on them being human shields, but Hamas isn't forcing them to stay. The people don't really have any other option.
Hamas and Israel are both treating the people in Gaza like human shields.