I think you've kind of oversimplified and mischaracterised patriotism here. You've basically constructed an indefensible strawman of patriotism, lit it on fire and asked people to justify saving it. It's a bit of a silly way to start a debate.
For example, patriotism is a good deal more complex than just saying "My country is the best because I was born in it". Patriotism is about loving your country more than any other, which doesn't necessarily entail thinking your country is the best, any more than loving your parents more than anyone else's parents doesn't entail thinking your parents were the best parents in the world. That analogy seems fairly pertinent given both the term and concept of patriotism comes from the old notion of "patrie" or homeland, which strongly connects the ideas of parenthood and nationhood. Even to this day, when one talks of patriotism, one is rarely far from the idea of "forefathers". Patriotism is far more about wanting to be a good contributor to your nation's legacy than it is about viewing your country's legacy as inherently good. Which isn't necessarily a defense of patriotism, but I don't think it's as straightforwardly narcissistic as you're making it out to be.
"You want to go back to being cavemen?" is just not even an argument. Cavemen also ate food and had sex, that doesn't make either of those things automatically undesirable. You're also just assuming we'll agree there's no value or validity in the continued existence of nationstates, which is not really something you can assume. Even if all national borders are entirely arbitrary (and a great deal of them are, no doubt), does that make all political relationships and moral duties arising from the existence of those borders arbitrary? I think you'll have to do some work to substantiate that claim, because if you don't, then it's a bit absurd for you to suggest it's automatically cavemanesque savagery for people to want to "defend their own territory" (not to mention there's arguably more arrogance contained in espousing a "civilisation" = good/"savagery" = bad binary than in patriotism). Also, it's just untrue that patriotism arises from caveman territorialism. It's verging on the offensive that you think you can boil down the complicated sociopolitical histories of the world's nations into "cavemen did it".
Does patriotism encourage you to always prioritise what's best for your country over all others? I don't think it does, I think that's nationalism. Again, since patriotism is love of own's country, patriotism doesn't entail always putting the good of your country above everything and everyone else any more than loving your wife means you'll always put her good above everything else. I mean, if my girlfriend wants to do something I consider unethical, I don't just go "eh, whatever's good for you" and go along with it, and I rather expect most patriots act similarly toward their country. Similarly, yes, you actually do need to explain why patriotism causes blind loyalty. Is there no dissent among patriots? Do all patriots follow the same political ideology? Has a patriot ever disagreed with the decisions of their state? If the answer to those question is "No", "No" and "Yes", then evidence strongly suggests patriotism doesn't cause blind loyalty. You can't just assert things to be true.
That comment about patriotic freedom movements being more about freedom than patriotism is just plainly untrue. The fact of the matter is that when you are an oppressed nation, nationhood and freedom are intimately linked to the extent that they are basically the same thing. When the reason you have no freedom is because the status of your nation is considered less than your oppressor's, how is it possible to agitate for freedom without loving your country, taking pride in it and wanting it to be valued equally among all nations? I mean, the issue is the same thing whether you approach it as gaining more freedom or increasing the standing of your country. That's not, of course, to preclude the possibility and actuality of patriotic dictators, it's just a specific response to your contention that freedom fighters weren't reeeeeeally patriots, which is just a poor attempt to deny the existence of evidence against your claim that patriotism is inherently evil.
Other thoughts not related to what you said:
1. Patriotism is the good it creates in the world. It's a form of love, and love isn't inherently good or evil. Patriotism has motivated bad things, like America's vulgar homeland intelligence and security apparatus. Patriotism has also motivated good things. Patriots are people who stand up and say "I love my country", but it's important to remember that "I love my country" can be, and often is, followed by "but I think it has lost its way, and we need to do X" or "and, because I am concerned for its moral health, I think we need to do X". And X isn't always some evil policy! X can be "reduce relative income inequality" or "create more employment opportunities for women" or "increase access to education among disadvantaged racial minorities" or "work to ameliorate the unequal construction of the international trade system that has resulted in the continued economic exploitation of the global south" or a raft of other policies that I, at least, would consider very good.
2. Patriotism is probably a valid feeling for anyone, but I think it's a particularly useful feeling in disadvantaged and excluded countries, like Haiti. The people who live in such countries are subject to systematic shaming. They're made to feel ashamed for being poor, for being black, for being of mixed heritage, for being Haitian. If patriotism provides them with a counternarrative to that shaming, if it allows them to take pride instead of being ashamed, I think that has to be a good thing. Right now, we think it's okay for an oppressed people to unite around the products of their oppression that make them feel bad.
It's like the Black Arts Movement in the United States. People think there's something racist about the BAM encouraging black people to embrace their blackness, to write in black vernacular and not feel they have to "clean themselves up" for the white man. But it's not racist at all, it's an opposition to racism. Racism has allowed blackness to be constructed by whites and forced on to black. Black pride allows black people to construct their own blackness, and take pride in it. Right now, we think it's fine for black rights activists to unite around poverty as an outcome of their oppression, but not their vernacular, even though that's just as much an outcome of their oppression, but it's one they can feel good about instead of just feeling shame, it's one they can utilise to create, whereas poverty is inherently debilitating.
Similarly, for the person born in Haiti, through the accident of colonial history, they live in a country with rampant disease and poverty and corruption. They live in a Haiti that was created for them by their oppressors. If you say patriotism is a bad thing, what you're effectively saying is that it's fine for Haitians to steep in their own poverty, in the negative outcomes of their oppression, but not embrace their language, their culture, and their community, the outcomes of their oppression that have positive potential.
tl;dr patriotism is ridiculously complicated and not inherently evil
