I never said I knew anything about a country I've never been too, but one can get a pretty good idea from studying history from books and on the internet.
I'll try to make it short: you are a relative newcomer here, so you may not realize that you are not the first one to come up with one of the statements like this: "All Poles are X", where X are usually derogatory, rarely neutral, and sometimes laudatory. But they all have something in common: logically, they are all false.
All Polish women are pack rats. False, some are.
All Polish women are beautiful. False again, some are.
All Polish woman have big tits. False again, some have.
All Poles are conservative. False again, some are.
And here comes your own statement: "Poles are collectivists at heart". [You did not use the quantifier "all" but you implied such.] So guess what? You statement is as much worth as the other statements, including the one about the tits.
And here is where I should really stop and conclude, since I assume you are a reasonable person, ready to recognize you own errors in judgement.
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But in case you are still prepared to fight the battles, I am willing to provide some extra "ammunition" here:
+ I assume that your research in this topic is very amateurish: you are not a scientist specializing in some field of social science or anthropology. You do not spent countless hours in some gloomy libraries researching the subject, you do not write scientific papers and you do not go through devastating peer reviews. You have nothing to stand on here. You are just an opinionated person, as anyone else here. In case I am wrong here, I am ready to apologize and revise some of this.
+ I do not know what kind of historical books you read. There are books and books. Some are really debatable. I also read tones of historical books, and papers. But that does not make me an expert. I am still an amateur.
+ Internet? You know as much as I do, that every Internet topic has both proponents and opponents. Not much help here.
+ How many people do you really know well enough to categorize them as individualistic vs. collective types? 100 maybe? 1000 at most. 10,000 impossible. So granting you these 1000 people, and making them accessible to you for yor research: what kind of methodology you have used to collect and analyse your data, compute statistical errors, and go through all these estimates in order to present us with your sweeping observation. If you did not do any of this, than again your conclusions are worthy exactly ZERO.
Here is you opening post:
The tight knit nature of the Polish family is one of the best things about their culture. The emphasis on loyalty to and pride in one's family and nation can't be any stronger. Although these are great things to have, doesn't Polish cultural mindset allow enough for people as individuals? If so, is this a recent thing or something jews brought to the table? In comparison with other nations, would you say that Poles are collectivists at heart?
I am going to ignore that bit about Jews because it sounds like a strange agenda. Other than that:
+ You do accept that Polish nation have produced some great leaders over centuries: political, military, cultural, scientific. Where did they come from, if not from very "individualistic attitudes" per se.
[The quotes in the sentences below are your own words]
+ So in your opinion, Joseph Conrad was "a collectivist at heart" or "an individualist" influenced by his "own ideas"? If the former, justify your claim based on his life and his literary works.
+ In your opinion, Maria Curie-Skodowska "was just stubborn and opinionated", or "just had to process idea through her head and follow her own will, whatever it may be?".
We could go on and on: for every single "collective" person from your pool of 1000 I could present you with a real life figure that strongly qualifies and individualistic: rebellious poets, vanguard theater directors, composers, mathematicians, painters, etc. Soon you would run out of your cases, believe me.
I rest my case.