The Garden of Eden, an honest explanation/discussion?

I have an understanding of the concept that is the Garden of Eden, a paradise on Earth where all creatures lived together in harmony devoid of the worst traits of humanity, but what happened to it? If God banished humans from the Garden how come it does not exist today as the garden was not just a home for humans but all creatures, were they banished with us or perhaps forced into becoming beasts of burden? I would like any sensible answer if I could, I am an atheist but like to explore the gospels and other religious works as I have an honest respect for anyone that dedicates themselves to study, no matter what there text. I was speaking to someone (a Christian) who truly believes the Garden of Eden was not on Earth but a paradise created by God (heaven maybe) that as a result of our actions as humans we removed from and therefore must dedicate our lives into doing good and repenting for these early sins, what do you think of that as well, sorry for the double question