Seems we live in an odd 'age' where someone who believes what the Bible says is called a "fundamentalist". Further, it would seem odd that if these events from Genesis and the OT were somehow untrue or allegories that Jesus would not have referenced the creation of Adam & Eve, being male and female in the beginning at their creation (Matthew 19:4), that He would go on to reference Jonah being in the belly of the great fish in His own time he would spend in a tomb (Matthew 12:40), and further go on to reference Noah in likeness to His 2nd coming (Matthew 24:37).
If I were a scribe or a pharisee back in Jesus' day, I'd have laughed Him right out of the synagogue if these events never happened, that they were just allegory. There is not a record of this - so we can only conclude that even the hypocrites of the day believed these events really happened. Further, these would be the worst references Jesus could have ever made if they didn't actually happen... as if to say, "Oh hey, remember when God blotted out all the life on land with a flood, like it says in my Father's word, but didn't really happen... yeah, that's what it's going to be like when I come back for My church... like a thief in the night baby, be ready!!" People would just be like [shoulder shrug], "not sure what's wrong with this guy, must've spent too much time out in the sun."
God was there when these things happened, it's in His word, and it seems Jesus (the word made flesh) was a bit of a "fundamentalist" when it came to the Father's word.