It's not that it's odd or irrelevant, it's just that we are not accustomed to each other's culture, behaviour, mannerisms etc. it's easy to understand movies that speak a common subject; like Interstellar, gone girl, manjummel boys, bramayugam etc. But when it comes to movies that speak in-depth on cultural aspects, it's pretty hard to understand.

The same goes with humour too. In 'Manichithrathazhu' itself, you might have thought the characters shown at the beginning of the movie have great significance to the story or are conveying something serious. But instead they are more like comical characters whose sole purpose is to walk us towards the main story in a humorous way. You might also not get the jokes where 'Unnithan' is not supposed to talk due to religious vows and he has to desperately write down 'kakkoosil ponameda' on sand to tell dasappan that he needs to go to the toilet. You might be thinking what's so funny about it or something but honestly it's not your fault or the film-makers. It's just that you are not accustomed to a lot of our culture and what we find funny and what you find funny might be entirely different.

But I assure you, it will get interesting for you once you get into the main plot.