once it clicks for you, reading Enoch will help a lot - that the Lord and his host were some kind of highly advanced people who were teaching them and giving them help so much of Genesis makes a lot more sense
i don't think that they exactly necessarily did things, but rather, knew things were going to happen and this knowledge gave them the advantage
like, the crossing of the red sea... if it was the Strait of Hormuz, it's not a very great distance to walk, 39km, so about 8 hours, which is pretty much spot on for an extremely rare low tide, and the depth of ... here is a map showing it:
on the western side, the current modern depth of the water is somewhere around 60m, but the important thing to note is that the entire body of water is very small, relatively speaking,
look, here's one that happened recently:
https://youtu.be/8frMAFwKD64
the sand that fills the basin moves around, also, and it is entirely plausible that during that time, the depth of a section of the strait was under 30m deep and a record low tide could expose the ground, and whoever got into it first would have about 8 hours to get through it before the high tide comes, and if you missed the window of opportunity you could find yourself 20km from shore so you better hope you can swim haha
i am pretty sure that's what happened... if it had not been opportune they would not have passed this way, but instead would have probably had to track further north to get across the suez
there is some small possibility that someone with high technology could have artificially blocked the ingress of the tide from the ocean via some very powerful pumps but that just doesn't seem likely or practical...
as for moving stones around, we know that someone back in those times knew how to do it... one of the major stones of stonehenge originated over 150km away from where it rests now, and there are other massive stones that have been found that were moved extraordinary distances back in those times, maybe some of them were done with canals that were long ago caved in but something else must have been going on
oh yeah, explosives of a sufficient size could possibly perform the required pumping action to accentuate an already low tide
water can take a long time to move through narrow channels like the Red Sea