Quran speaks of a local flood, not a global flood.
Two points here,
1. Where in the Quran story does it use the word "local" to describe the flood?
2. Even if it does that simply makes the Quran version a post-hoc rationalisation of an earlier myth.
Some other stories from the Quran that a number of folks would consider mythological;
1A. Jesus blows on a clay bird and it comes to life
'behold! thou makest out of clay, as it were, the figure of a bird, by My leave, and thou breathest into it and it becometh a bird by My leave, Yusuf Ali Quran 5:110
2B Solomon and the talking ants and birds;
Yusuf Ali Quran 27
'16. And Solomon was David’s heir. He said : “ O ye people ! We have been taught the speech Of Birds, and on us Has been bestowed (a little) Of all things : this is Indeed Grace manifest (from God.) ”
17. And before Solomon were marshalled His hosts,—of Jinns and men And birds, and they were all Kept in order and ranks.
18. At length, when they came To a (lowly) valley of ants, One of the ants said : “ O ye ants, get into Your habitations, lest Solomon And his hosts crush you (Under foot) without knowing it.”