The world is an illusion. This is a view held by Vedanta, Sikhism, Buddhism, Plato, Arthur Schopenhauer, Christian Science, and A Course In Miracles.

Contradicting this view is your own sense experience of realness, the constancy
of stimulus, the enduring nature of time and events.

Which view is correct? The idea of the illusion or your experience of the realness?

This answer proposes an objective observer, one who is not part of the system that is being observed.