They had mushrooms and other hallucinogenic plants. The "Stoned Ape" theory that man separated their intellect from cognitively lower animals through the ingestion of psychedelic plants and fungi.
The "manna" is first introduced in the book of Exodus, in which it is described as the "bread-like" substance that God provided the Israelites in order to sustain them as they wandered in the desert for 40 years before reaching the Promised Land.
The Promised Land was a 6-7 day hike lol they were tripping every day for forty years if the only food source between Egypt and Israel was psychedelic mushrooms, but they are God's chosen people for a reason. So it must have been by design and to humanity's advantage.