History humblest senior brother.

It mostly depends on the culture, I have never been to china, and i do not know anybody from there, my only knowledge comes from novels and stuff i have seen online, and from what little i have seen this looks to be the standard response in chinese culture. I know that in european and american culture there are more types of answers to this question from the narcissistic "yeah i'm amazing" to the humble one "it's not so hard/important/etc" or another one its the explanation one, "yeah i did find that but it was because i had access to these resources and i found out the technique in a ruin", most of the novels we read that are translated do not have this type of answer, i suspect that this type of answer its very unlikely in china, they go for full secrecy, never say any detail about anything, just go for standard polite humble answer #1, on the other hand in the west we have the explanation answer, explain a bit without ever touching on any important fact, of course in the culture that the authors write for their books, it is a culture of total lawlessness, going for full secrecy may end up being the right answer since anyone with the right ammount of power/money could simply kidnap you and torture you for your secrets Without suffering any consequences from the "Law" since if you are powerfull enough not even the government can touch you.

So for my part yeah its tiring seeing the character always answer with the same "humble" answer, but taking into account the type of world that the author have created it may actually be the only smart choice left, as I say before this could be because of how chinese culture is or it may be authors choices ( I suspect chinese culture because so many authors do it, it is practically everywhere) 

Instead of "thanks", "Oh, no, uncle you overpraised me! It's not that big deal" have longer word count.  

One thing you will notice when reading this novel that Yan Zhaoge loves the humble-brag. He is a very arrogant, but likes to come off as a humble, low-key person. So, yes, his style of speech is partly due to Chinese culture, but it's also due to his personality. Other characters do point this out every now and again, most notably Feng Yunsheng. 

that probably just means that you got high on some praise, became an arrogant asshole, fell down and noticed it and now need praise to get back to a normal level of self esteem
you probably aren't really cute nor handsome, just normal (in your parents eyes you are probably both though)
this is however another thing, since the MCs (in question) know how awesome what they did is but don't accept deserved praise. You may or may not be right about you not deserving the praise, so there it is another issue
good luck getting high selfesteem again, though (watch some videos on YT about that, there are some good ones) 

Ahh, how can i forget about this part of CN novels world... 

Like, when you get A+ and your mom praise you, usualy you says something like "thanks mom" and not "nah, you overprised me". This is normal thing imo. 

Idk if it's a culture gap or another symptom of the collective disease web novel authors seem to suffer from that makes them all just ever so slightly brain damaged, but it is what it is. It's just meant to be a polite reply. Nothing more, nothing less. 

What the heck with his infinity humble attitude to every single praise?

Someone1: Zhaoge, you're easily winning against #enemyname#. What a great achievement!
Zhaoge: Oh, no, uncle you overpraised me! It's not that big deal.
Someone1: *wtf are you talking about it's very damn huge deal*

Someone2: Oh, Zhaoge you cure this incurable disease, what a great achievement!
Zhaoge: Oh you overestimate my achievement in this case...
Someone2: *wha...? Is he serious or just trolling me, im damn first rate alchemist and never heard of this method before... little bastard*.

Soooo, why the heck he never take any praise just as normal people? 

"Of course, what do you expect from a peerless genius like me? Don't you even think about it, you wouldn't be able to begin to comprehend my peerless achievement."  

I mean people outside of my family have also told me the same thing (as in smart and good looking), so Im pretty sure they wouldn't lie, but I don't want to let myself get high on my own ego again. But according to everyone else I beat my self down. Maybe I do beat myself down subconsciously. But I get what you're talking about with the novel, that he doesn't really own up despite knowing it's a big deal. Pretty fun ngl to see people busting a vein from him trying to be humble. 

That's exactly what's irritate me to no end. I mean if every single time when your axhievement has been praised, you just say "oh, you overprised me", even if it's clearly deserved praise. 

Well normal people do accept praise exactly like that. That's common courtesy....... else they are though of as narcissist