The many-worlds interpretation doesn't say that when we interact with anyone we actually interact with ourselves. It simply says that all the permutations and combinations of our lives (infinite possibilities) all exist in the multiverse at the same time.

Everything being one, is another concept which says that the entire existence is simply one energy and we stem from that energy. And yes, this is a realisation that would change everyone for the better.

Will surely give that a read. Thanks for sharing!