Why do you think they've chosen 'corners' here when they could have simply used the Hebrew word for 'all over'. I'm aware that Kanaph ís often translated as 'extremities', but it changes nothing as extremities is just another word for saying 'ends'.

To me and many scholars it's quite obvious they wrote this down as if they thought the earth had boundaries, where in reality it's a sphere that has no boundaries.

Perhaps the sea had no relevance in this case, perhaps they meant the boundaries of land (not earth) you can live on, but fact is the text isn't specific enough about what's really meant here.

Also, other parts of the Bible do not clarify that earth is believed to be a sphere either, quite the contrary;



A circle? A curtain? A tent? At best this a the description of a flat circular surface with half a sphere (of the sky above) on top.



'The Creator of the extremities of the earth'... sounds like the entire earth was meant after all.



and



If a text doesn't clarify what is meant with whatever shape it would mention, it still doesn't really mean anything. For example your pillow example shows that even though it may have four corners, how the three dimensional space was thought to be the earth is still open for debate so to speak as it isn't clarified. The upper part of the pillow may be a representation of the sky instead of earth itself.

It has little to do with presumptions and a lot to do with texts not being specific enough to really determine the world view. In my opinion it is very unlikely that they thought the earth was spherical.

Or how do you explain that sometimes the fly drosophila is born with four wings instead two? Hey, that's mutation

How does the continental drift fit to creationism