And that is exactly what our Biblical ancestors did. If we take the Jewish tradition, it seems that this is not just a vague folk memory, but a huge effort to convey a historical message to future generations. The Biblical documents in great detail everything related to the Exodus from Egypt and the giving of Torah: dates, names, ages, attribution, exact location, the order of events, and so on. This is not some “once upon a time” legend.
Also, there is a whole system of commandments designed to preserve this historical memory: In every prayer, every day, on Sabbaths and holidays, the Exodus is mentioned countless times. Passover and Seder night were built specifically to preserve the same tradition and pass it on to future generations.
Indeed, the same tradition has been preserved for thousands of years, among millions of Jews who are living in various communities all over the world. This is not a vague testimony of some senile old men, but a living testimony of an entire people who gave their lives against all difficulties to pass it on.
One can always doubt, but as we have seen above, like memory and trust, such a tradition is not a factor that can be undone with a wave of the hand. Whoever does so will find that the same skepticism can be directed towards any other field of research, thereby undermining all the stories of archeology and history that are at once known to man as passed down from the ages.
For if the living testimony of an entire people is meaningless, then even some ancient inscription, dubious document or even photographs, therefore proves nothing.