So I will answer you in English too, please excuse some mistakes I will make 😉

I am a 25 years old French guy and lived in Paris, Tours, and Nantes (west of the France, not Normandy neither Midi). I think the following rules apply to all France, except for maybe some old people or really small parts that still speak old French.

The "passé simple" tense is a literary tense as you said. It is rarely used in oral conversations, but it is for special cases: journalists talking about a serious subject or in a discussion that is really REALLY formal.

You will rarely hear something like "hier, j’eu pris mon vélo" or "en sortant de chez le coiffeur, je pris mon vélo". The "passé composé" tense is used way more often and the "passé simple" is considered an old and formal tense. Actually, the last time I heard it in a conversation, it was from an American 😉

It’s the first I’ve heard about the passé simple being used in spoken French more in Normandy than in other parts of France. I spend a lot of time there and that does not seem to be the case.

A couple of hours ago I’d have told you that yes of course the passé simple is used in oral speech in the south of France. I knew that was the case some forty years back when I lived there.
But I’ve been doing a little research before answering and that was fortunate because I came across this paper that deals with this issue with what I find are good references*.

Au XXIe siècle on utilise moins le passé simple, à l‟oral on l‟entend dans certains
dialectes : « -Dans le midi le passé simple est encore vivant » (Grevisse, 2008, §882a).
Par contre, Claire Blanche-Benveniste écrit dans Approches de la langue parlée en français :
« On a souvent dit que le passé simple était plus répandu dans le sud de la France. […]
L‟observation, qui valait sans doute encore au début du siècle, ne vaut plus aujourd‟hui.
L‟utilisation du passé simple semble ne plus rien devoir aux régions. » (1997, p. 53)

So it seems that linguists are divided on that issue.

It was a well-known fact though, that in the south of France, in the area of Occitan influence, people have continued using the passé simple well after it had nearly completely died out elsewhere. Probably because the passé simple exists in the Occitan language and until the mid twentieth century quite a number of people still spoke Occitan in everyday life (at least in rural areas).

It is nevertheless still present in written French as this paper concludes, mainly in literature, fairy tales and newspaper articles.

You might be interested in this earlier answer on French Language that has a more historical perspective on the disappearance of the passé simple and its comparative use with the passé composé.

• _{Grevisse, Claire Blanche Benveniste and Henriette Walter are linguists that one can trust.}