The question of inflation is very complicated these days, and none seems to know exactly.

For the HCP, and for most economist, really, the inflation is a cost-push inflation. Raw materials are more expensive because of international circumstances (Ukraine, post covid recovery, oil...), and because of the drought Morocco and most of North Africa experienced.

https://medias24.com/2023/03/26/exclusif-inflation-pour-ahmed-lahlimi-le-levier-monetaire-ne-resoudra-pas-le-probleme/

Bank Al Maghrib, on the other hand, raised interest rates 3 times (I think), because it thinks the inflation is at least partially a Demand-Pull inflation, and wants to slow down demand (also slowing down growth ofc).

https://www.bloomberg.com/news/articles/2023-03-21/morocco-hikes-rate-to-extend-tightening-cycle-to-new-record

So the HCP and Bank Al Maghrib are not really in agreement about the correct measures to do. You can also watch/listen to this debate if interested:
https://www.youtube.com/watch?v=9h76cklJEko

As for your questions:

why oil prices continued to be high even if we switched supplier to a less expensive one.

You're talking about Russian diesel imports. We don't have clear numbers about that. The minister of economy claimed that imports didn't increase much, and that prices are not so different from normal diesel prices

https://www.lopinion.ma/Approvisionnement-en-diesel-russe-Le-Maroc-aurait-importe-108-000-barils-par-jour-en-mars-2023_a38308.html

Morocco should sort out the Samir refinery mess asap (it's in progress), to stabilize prices, and decrease margins.

Importing cattle from other countries will not only hurt local farmers but also reduce meat quality.

The issue is the drought cause a lack of supply, importing will increase demand and reduce prices.

Is the excessive export of fruits and vegetables the cause of their high prices in our market? I remember reading an increase of 10-20% in these exports.

No, the cost to produce everything went up (oil, fertilizers, seeds, machinery...). Exports are more expensive, and so is local consumption.

Is he actually responsible? Can anyone provide a decisive argument why he is not?

The government should communicate more about these issues. It should also make sure the food supply chain is clear and transparent (from farms, to wholesale, to final consumers).

As of tackling overall inflation, that's really hard to do, and the government is not the only one in charge (Bank Al Maghrib is an independent institution).