Hello!
I'm just wondering how did cereals became staple foods world wide, when we're ill suited to eat them. They have tough bran our teeth can't grind, and we can't digest. Small seeds that's not practical to collect with our large hands.
Also it's very labor intensive to produce. Plowing, sewing, harvesting, thrashing(, grinding).
In contrast (starchy or not) root vegetables can just be sewn/planted than plucked from the ground and eaten directly, maybe even without cooking. Fruit or nut bearing trees that we can directly eat, that require little maintenance when the trees are mature.
Although there may be some people who can answer this here, questions of how and why agriculture developed is not something a historian would normally try to research because it is pre-historical, i.e. from before writing was invented. This distinction may seem somewhat arbitrary, but it is what it is.
Subs like r/AskAnthropology/, /r/Anthropology or /r/AskScience may already have answer to the question and/or have more people who can answer this specific question.