Gen 1-2 definitely didn't happen and were written by two different groups with different religious views using two different creator-god names
Noah's Ark definitely didn't happen, and the story repeats itself all the time because it crushes together the Yahwist's and Elohist's writing in a manner especially suggestive of natural human authorship
New Testament claims that the human lineage is as young as is reported in Gen 2 (Luk 3:38) and has Jesus - presumably the same entity as God - suggest multiple times in two gospels that the great flood was a real event
That's about enough to deconvert already, and it keeps getting worse the deeper you take things