"I AM" is simply the translation from Hebrew of a verb. Hebrew has no verb tense of past, present or future so "I AM" simply means I was, I am, and I will be. I don't think Jesus meant that to be exclusive to him.

As an OT prophet said- "What is has been before and will be again". I'm not an Atheist, but I think he wrote that atheists claim to have no answers, either. Not that you or I are wrong about the existence of God but that they don't believe the same.