We might say that C.S. Lewis is omnipresent to Narnia insofar as He makes Narnia (and every reality in it) to be. Lewis is present in Narnia as efficient cause.
Upon further reflection, we discover that God’s presence in the tabernacle/temple is a sign of God’s future presence in Christ (the Incarnation), and God’s special presence by grace in believers (our union with Christ).
The Garden of Eden is the first sanctuary where God makes his home with man, and after the Fall, the story of the Bible is how God and man can eventually live together again.