Likewise, had the Bolshevik Revolution failed, as did similar uprisings in Hungary and Germany, tens of millions of human lives would have been spared. Tsarism was an oppressive system, to be sure, but it was benign in comparison with the butchery of Lenin, Stalin, and their henchmen. Moreover, Russian civilization and even the mental state of Russians were decimated by 70 years of oppression almost unparalleled in human history.
Those among the Founders were universal in their belief that Slavery was an evil and worked to reduce its spread. Jefferson was instrumental in that effort in Congress. Only decades later did the leaders of the South reject the Founders views and proclaim it a good for all concerned even the slave. After a few decades of such nonsense the mentality of the South was warped so badly it took the death of the culture to straighten it out.
Tsarism was dead before Lenin took power and there were no forces capable of defeating his followers on hand. Not only were domestic opponents defeated but an international intervention as well. Bolshevism won the field because it was the strongest force there. Would it have won without the intervention of the German army? Don't know.