That is an excellent attempt to frame a situation to your perspective, as flawed as it is.
This is not a Declaration of Independence moment. It is not dealing with internal dynamics of populations and demographics (though the Russians are in Ukraine only through the starving of millions of Ukrainians and the illegal implanting of Russians into Ukraine during the Soviet era).
Crimea is a pure play of an external country simply illegally annexing the land for strategic value. The Russians are starved of great ports and especially southern ports for their navies.
Russians create they false pretexts to invade other countries. You’ve fallen for a deflection about nothing. The deflection is meant to distract from the fact that the Russians have invaded the entire country.
Weak-minded individuals fall for Russian propaganda and it’s nothing to be ashamed of, it’s just the reality.
It isn’t for you to decide which people have a right to self-determination, and which people don’t have a right to self-determination.
Neither is it up to Putin, Stalin, Lenin, or any Czar. Neither was it up to Attila the Hun, Genghis Khan or any of his successors, neither was it up to any Ottoman ruler, or Timur, or Alexander the Great, or Napoleon, or Hitler. I don’t care that any of them were conquerors. The right of conquest may have ruled in the past, but we are seeking to establish the rule of law.
The American view is the right of self-determination, and we will eventually establish this throughout the world. A hundred years ago, this view was hopelessly idealist and was. misused by the victorious powers of WWI to make a lot of mischief, setting the stage for a more awful war in mid century. Today, the response of the democratic countries of the world to the invasion of Ukraine reveals the right of self-determination to be within our grasp. And by the same argument that the people of Ukraine are the ones to determine their future, the people of the breakaway republics and of Crimea are the ones to determine theirs.