Many years ago I was witnessing to a guy who had spent some time in Central America with the Peace Corps. There he was introduced to Millenarian thought. In fact, while there he converted to the baha'i faith.
He went as far as reading the Revelation Grand Climax book. He was struck by how similar it sounded to the ideas he was exposed to in Central America, particularly from a Seventh Day Adventist couple he was close to.
It didn't really sink in at the time, but years later after I left the religion and began doing some research it all started coming into focus. Conditional immortality, anti-trinitarianism, gentile times...their eschatology in general, pacifism, Russell was part of a greater movement and many other denominations maintain similar positions on issues which at one time I thought were almost unique to JWism.
Rutherford was able to build a viable religious organization and Knorr after him was able to capitalize on the post WWII environment to grow it into what it is today. Most off the other branches that emerged after the Great Disappointment of 1844 weren't as successful, but that doesn't mean that Russell had any unique insights.