God's redemption of the Israelites is a redemption for a purpose, a purpose that doesn't become clear until we get to Sinai, for at Sinai the Israelites will become God's people, bound by a covenant.
The genius of the film is that Schnabel realizes that there's a lot of pain in it, but there's also a lot of redemption in this extraordinary act of art, and Schnabel doesn't try to oversell you on that in any way.