Is it possible to pass through the hub or main street when people are waiting for the parades and fireworks?
Yes, the cast members keep a section open closest to the store fronts open as a walkway and enforce guests to keep moving. Up until the parade/fireworks start, you’ll be able to move freely through the streets as well.
A lot of the stores connect as well. We often avoid the crowds (and the heat!) by walking through the stores and scooting to the sidewalk when we need to.