What were the odds of a soldier dying, who’s positioned at the front of the line during a medieval battle?

Higher than the combatant would hope, less than media leads us to expect. More can always be said if anyone would like to contribute further; for the meantime, OP, these previous posts should address your concern:

u/Iphikrates and u/Iguana_on_a_stick on how the front line combat issue applied for the Greeks and Romans;
while u/Hergrim examines both how it went for the Medievals and how casualties actually accrue, and in a previous post also linked there, examines the willingness to get into close combat.