Indeed, Rabbi Shlomo Ganzfried explains that the obligation for one to see oneself as if they personally left Egypt begins with the section of protection, as it says "our ancestors were idol worshipers." Just as a person must see themselves as if they left Egypt, they must also see themselves as if they were once idol worshippers, and now they have come close to serving God. And today, tonight, they have begun to serve God by observing the commandments practiced on that night.