I’m sure there are multiple purposes to most things in the Bible. It’s a hyperlinked text where something here references something there, there, and there. It’s a very deep and interwoven text. The stories in the Bible relate to other events and stories. As far as unusual or miraculous events, well that’s just it, they are unusual. Lots of mundane things happened too, but there’s not a useful reason to record them. Imagine the length of the Bible if Noah’s entire itinerary was included. “and on the 34th day of the flood, Noah washed some clothes and made a sandwich. And the meat in the sandwich was chicken. And upon the sandwich was a layer of bread, as it was also beneath the sandwich”. That would be a really long book!
I don’t think it’s meant directly to humble, but to show the mighty events that have happened, which is by itself humbling. So it serves to inform, to humble, and to continue the narrative of God reaching out to the human race.
There’s also a current ideology of not realizing how many crazy things are going on today. 1000 years ago if you had told someone that they are covered in invisible bugs that make you sick, they’d think you were crazy. If you told them you were on a ball that spins around another ball that spins around a spiral of balls that is fixing to collide with another spiral of balls…in like a few billion years…they’d think that was crazy or amazing. Yet it’s happening. I see the story of Noah as no more unbelievable than telling someone, without pictures, the story of WWII in about 3000 years.