Yes ... We draw an arbitrary boundary ourselves described by the pronoun "I", and then we have the fuzzy bits of "my" and "mine".
In reality all kinds of molecules, atoms and ions are exchanging in and out of our bodies. To be fair the exchange is slower in the brainy bits. I think the phrase inter-relationship in reality is an understatement. Indra's net perhaps gives a better analogy. Similarly, for more nebulous bits like ideas and beliefs. Our material goods exchange, monies exchange.
For me, connection is a 'better' word. We are connected to the the rest of existence, at the very smallest to the very largest scales; through the depths of time.
If someone were to ask me, "are you religious?" I would have to answer, "no, but I am perhaps ligious." For I am connected to the universe and don't need reconnection.