Lenin was a political opportunist and Stalin most likely faked Lenin's will to appoint himself after his death. The Bolsheviks also murdered/incarcerated plenty of leftists and disempowered the pre-existing worker coops and trade unions through centralization.

Anarchists, syndicalists and other leftists were literally building decentralized structures before the Bolsheviks swooped in and decided the public would need decades of ideological education before it could be trusted to make any decisions about their lives and "helpfully" started making the decisions for them. It doesn't help that many of the leftists outside Russia who were critical of Bolshevism were murdered by German paramilitaries and later more indirectly by the USSR while trying to fight fascism in Spain.

Saying you have a good understanding what "left" is because you were born in the USSR is like saying you have a good understanding of what pasta is because you've been eating Yum Yum noodles for a decade.

Have you read Kropotkin? Bakunin? Proudhon? Bookchin? There is a wide range of leftist thought outside the very narrow niche within Marxist-Leninist-Maoism that still uncritically defends the USSR.