Noah was not judged by the work God and Christ did on the cross because Christ had not come to complete God's plan for salvation. But every soul alive since Christ's sacrifice are judged by whether they accept Him as Lord and are born again. You said Jesus' death on the cross saves us, but it does not save us if we reject him. Do you think Jesus took all our sins and paid the price on the cross and now everyone on earth has some ticket to heaven if they're halfway good and think there is a God out there somewhere?
Well gosh. All the poor souls who the apostles did not get to after they went into the world to preach the gospel are doomed if one follows your logic. It took centuries to spread the gospel and I expect it has still not reached some people even today. So I don't accept this premise exactly as you have stated it. Paul himself spoke of those who not having heard the gospel "follow the law that is written on their hearts." It is called in theology Natural Law. Noah I think was one of the ones "in prison" to whom Jesus preached when he went to the underworld.