The article does a poor job at explaining the complexity of the theological issues. It seems to be written by a secularist who believes that the only logical alternatives are that every word of the bible is literally given by God to Moses or that the bible is only a primitive "mythology" that perhaps contains important lessons for us today (written in a patronizing tone suggesting only primitive people need the myths). But even if intervening humans transmitted the bible until its text became fixed, the secularist bias is apparent in the assumption that God could play no role in that process.
In any event, there is a lesson in the Passover seder service, in which we teach children that we must create the mindset that we, too, personally were slaves in Egypt and were freed from bondage by God. Our lives are not to be lived differently because we personally did not happen to have been born in slavery. So, what if there was only one Jew ever taken into slavery in Egypt (does anyone believe that no single Jew was ever, for any reason, made a slave???)and the rest is embellishment? It makes no difference. God wants us to personally identify with slavery and credit God for our freedom. For thousands of years Jews have been adopting this mindset.
Historical honesty and truth are important, but it is a mistake to think that the legitimacy of one's religion or the truth of divine presence in one's sacred books hinges on the findings of archeologists.