It is a historically true parable. More than one level of understanding. Hidden pearls in many places... you could say without the signified language of Christ (parables) he spoke not.
True to the actual events and times with the gospel message hid. Just like the whole period there were kings in Israel and the use of ceremonial law and its signified language using metaphors to represent the clean as those born again and the unclean those who have no faith.
Noah it would seem was given the spirit understanding hid in parables .They as metaphors in those parables spoke of the suffering of Christ beforehand .The gospel mixed with faith giving them rest in their work. Having received the end of their salvation from the beginning as us .
We look back to the Ark it looked ahead to Christ our righteousness and the glory that followed .The graves were opened... opening the gates of the ressurection
Searching what, or what manner of time the Spirit of Christ which was in them did signify, when it testified beforehand the sufferings of Christ, and the glory that should follow.1 Peter 1:11
The Ark as a metaphor represents Christ. it was seed as a source of unseen faith, the gospel...... or letter of the law to all it killed.
Hebrews 11:7 By faith Noah, being warned by God concerning events
as yet unseen, in reverent fear constructed an ark for the saving of his household. By this he
condemned the world and became an heir of the righteousness that comes by faith.
2 Peter 2:5 if he did not spare the ancient world, but preserved
Noah, a herald of righteousness, with seven others, when he brought a flood upon the world of the ungodly;