A lot of it can be explained however with simple insight into how fairy tale stories develop from an outstanding experience:
God-made gardens => Explorers probably saw a lot of nice things with unique features, poisonous trees or shamans that promised such a land when groups of people travelled and stories about it probably went from generation to generation and became better and better until they were written down and interpreted as fact.
Talking snakes => Probably somebody that ate or came near the wrong tree and started hallucinating. Certain grains, fungi and mushrooms do induce such things. Did you know potato's are also poisonous? And tomato's were long thought of as poisonous as well. Stories about how people got to eat certain things (current day eat-your-veggie stories).
Humans living to 900 + years => Immortality and near-immortality is a typical story device. A lot of stories revolve around how people found immortality and couldn't live with it.
Men who turn sticks into snakes => Magic tricks - as the story shows, both Egyptians and Israelite magicians were able to fool the others perception of reality. Bunny in the hat trick.
Men who stop the "sun" => Legends and exaggerated stories about how one army defeated the other. Such an event would've messed a lot of things up (things such as tides, gravity and even climate). It would also have been noticed by such sun cultures like the Celts, the Mayans etc.
Men who have extraordinary strength as long as they avoid a haircut => Legends and exaggerated stories about a local war hero.
Food falling from the sky => I don't know, it looked like snow so maybe somebody interpreted a snow-in-the-desert (very rare but not impossible) story where somebody survived because of the water it provided.
Angels wiping out massive armies in seconds => Can be explained by disease in a war camp. Also, the whole army gets wiped out but the king and his entourage stay alive?
Talking donkeys => Somebody ate the wrong mushroom.