Anyone who’s not a Nord is regarded as absolute shit by many Stormcloak supporters, especially within Windhelm.
Then why is it that all races are accepted into the ranks of the rebellion? We see Redguards and Imperials joining them in-game, and Galmar himself explicitly states that he has nothing against non-Nords but instead focuses on what their intentions are and where their loyalties lie.
Take a look at the way Dark Elves are Argonians are treated there - Argonian’s aren’t even allowed to live inside city walls. This was by Ulfric’s degree. (In my playthrough I’ve ended the rebellion and a line of dialogue spoken by Scouts-Many-Marshes, an Argonian dockworker in Wildhelm, confirms this. The Dark Elves and Argonians in Windhelm all seem to be a lot happier now that racism is no longer literally enforced by the Jarl.)
The Argonians are kept out of the city because of their history of extreme violence and slavery with the elves. The Dunmer had an active slave trade industry for thousands of years against pretty much every race, but specifically targeted Black Marsh to get prisoners from. They even went to war when their victims defended themselves against one of the traders. When you consider how dangerous Argonians can be with their connection to the Hist (like when they invaded Oblivion during the last game) it makes sense to keep a group of them separate from a group of their former oppressors, especially with a guard force stretched thin by war. And get this, Brunwulf himself admits that it isn’t safe for them to be let inside the city yet. He goes around with this air of social justice making promises of equality, but doesn’t follow through when actually given the power to change things.
All over Skyrim there are Nords that scream racial slurs at you during battle when you’re playing as an Elf, Argonian or Khajiit
This is just because of the ways people address each other in TES games. In Oblivion the Nords were referred to as snowmen and savages. In Morrowind the Dunmer hated pretty much everyone, including other dark elves that weren’t originally from there. In any case, what slurs are you talking about? Calling a race that looks like a cat a cat, or like a lizard a lizard, is just a different term for them. It’s like calling someone a man instead of specifying them as a Redguard or Breton.
along with cries of “Skyrim belongs to the Nords!” (That dialogue isn’t specific to Stormcloaks, but I can’t recall ever hearing it from Legionnaires so I assume we’re meant to perceive NPCs who use that dialogue as supporters of the rebellion. That’s just my speculation so take it as you will.)
That’s a political statement in the context of the civil war. They just want to rule themselves and be free from the corrupt bureaucracy that betrayed them and allows a supremacist force to commit genocide against them for their beliefs. It isn’t “Skyrim belongs to the Nords, everybody else leave,” it’s “Skyrim belongs to the Nords, not to the empire.”
Ulfric’s role in the Markarth Incident and his subsequent actions are also very annoying. Ulfric made a deal with someone who couldn’t really enforce what he was promising. Signing the White-Gold Concordat and therefore outlawing the worship of Talos was the only way to end the great war and get the Almeri Dominion to screw off for a while so the Empire could recoup and come up with a proper game plan, and going back on any part of that treaty would be a Tremendously Bad Idea. Igmund wasn’t even Jarl at the time of making the deal with Ulfric and is a strong supporter of the Empire - I’m 98% sure he knew he wouldn’t be able to keep his end of the deal and just spouted some bullshit to get Ulfric to do the dirty work for him, and he was pretty quick to cut all contact with Ulfric once his neck was on the line. Markarth was peaceful under the rule of the Reachmen but Igmund wanted to be Jarl and Ulfric wanted to keep worshipping his favorite Divine in public, so Ulfric ended up slaughtering a lot of people to get what he wanted.
Even in the sight of most Empire supporters, the book detailing the Markarth Incident is widely regarded as pure propaganda. Nothing in it about Ulfric’s massacre is corroborated by characters in-game, and some NPC anecdotes outright go against it. One of the prisoners in the mine rebukes Ulfric for killing his daughter, but according to his testimony she was murdered some two years after Ulfric left the city.
When he didn’t get his way he got really pissed off and took the opportunity to kill High King Torygg and start a huge civil war that weakened Skyrim as a whole and used up a ton of the Imperial Legion’s resources, therefore making it a lot easier for the Aldmeri Dominion to keep their grip on Skyrim. The High King had thought highly of Ulfric and probably would’ve given real consideration to Ulfric’s desire to have Skyrim cede from the Empire and keep fighting the Aldmeri Dominion as Hammerfell had done, but instead of diplomacy and a grown-up conversation Ulfric decided to challenge Torygg to a battle he knew he would win so he could rule Skyrim himself. Kind of like what the Aldmeri Dominion did to the Empire. (That is in bold and italicized for emphasis because it’s actually a really amazing parallel, the plot for Skyrim is so well-written holy shit.)
Ulfric did approach Torygg with a plea for independence at the moot that named him king. Torygg listened and found Ulfric’s words impressive, but stayed with the empire because of how much they were paying him. If he didn’t listen then, he wasn’t going to listen again, and approaching him with words of treason would have been political and literal suicide for Ulfric with the strong imperial presence in Solitude.
The Aldmeri Dominion started a war on they Empire that they were going to win. The Empire was having none of that and decided to suck it up and sign the Dominion’s treaty - the White-Gold Concordat - so the war would end and it’d be able to come up with the resources to really take on the Dominion. The terms of the treaty are really horrible and the only thing in it for the Empire is that the war would cease, but it did what it had to to prevent more lives from being lost in a war it had no chance of winning.
The Dominion was hurting just as much as the empire before the treaty was signed. Their army was all but destroyed in Cyrodiil and the capital was retaken, but the emperor just gave up to stop the fighting. The only reason the Dominion attacked the empire in the first place is because they were high off the success of ambushing them - the original plan was only to take Hammerfell.
Reasons why the empire is not awesome:
The empire has never brought peace or security to Tamriel. Time and again they have abandoned other provinces to look out for number one, withdrawing troops to Cyrodiil in times of crisis and allowing their own citizens to be slaughtered. They didn’t care about the Orcs constantly having to rebuild after getting raided by Bretons, they didn’t care about stopping the slave trade in Morrowind, and they didn’t care about keeping a watchful eye on Vardenfell so the Dominion couldn’t swoop in effortlessly.
Also, bear in mind that imperialism in and of itself is a horribly racist form of government. It sets up one central culture and dominant and makes other cultures rely on its superior influence to progress and stay in line. Look at some of the things general Tullius says about Nords being lawless savages, regardless of whether he’s talking to his enemies or the people he’s trying to protect. Everything he says is just complete disdain for their religion and society, and he makes it very clear that this is just another war to be won for the sake of bolstering the empire rather than doing what’s best for the people, since they clearly have the means to defend itself. He knows that Skyrim doesn’t need the empire, but the empire clearly needs Skyrim.