This is incorrect, both regarding the political structure of the USSR, and regarding the left/right divide.
For starters, the USSR had strong localized democracy. It was also a planned economy, as is the basis of the Marxist conception of socialism. Workers formed soviets, or worker's councils, and these laddered up from the local level all the way up to the supreme soviet. In this manner, production was collectivized and run along a common plan. Those at the top of society were on average 10 times wealthier than those on the bottom, as compared to hundreds to millions range for feudalism and capitalism.


Secondly, the left/right divide is about social relations to the means of production. Leftism is generally about collectivized ownership and production, and rightism is about private ownership. The USSR was a publicly owned and run economy, and while it certainly had flaws and struggles, was unquestionably on the left. An example of a right-wing economy with a small, priveledged elite would be the US, or the Republic of Korea, under the control of the chaebol.
Overall, Marxism-Leninism is the most widely adopted and successful tendency within Marxism, and Marxism itself is one of the two largest umbrellas in leftism, the other being anarchism.