Understanding non-self, life and rebirth

Blessings to all, I have had a difficult time trying to understand what it means by "non-self". I am certainly no expert in Buddhism but I was wondering if this life we have is just some subset of this ginormous pool of energy. Let me try to be more clear with an example. Suppose there is a big lake. If I drink a glass of water from this lake, now living inside of me, this water is still water and it would not be wise for anyone to say 'no that water is me'. This water one day leaves the body and goes back to some big pool of water ( which may contain some different type energy/ vibrations by being inside of me) and may enter into an animal/ human someday. So my question again is do I think of this life that I identify myself with is also some common source of energy or element like water? Is this what non-self is? We are all part of one big source of energy? I apologize if this is a bad example but I hope I made myself somewhat clear. Thanks!