All Russians believe this, true. The Ukrainians don't, they have a different language, alphabet, and history.
During the second world war, the Germans invading Ukraine were greeted as liberators. Kyiv surrendered without firing a shot, While the Ukrainians quickly learned there was no difference between a Russian and a German jackboot, it has enabled the Russians ever since to label them as Nazis.
War is theft writ large. Ukraine has 25% of the world's chernozems, the richest agricultural soil on the planet. I hope you understand this.