In a "balancing" action, Jesus (a perfect man) died to offset the sin of Adam (a perfect man). So, Jesus died for our sins, became the "ransom sacrifice", so that we are entitled to salvation.
However (starting in 1995?) Jesus is not the intermediary betwen God and most JWs. A select group of JWs (the "anointed" 144,000 that are going to Heaven) have Jesus as their intermediary with God, and so can receive salvation from God through Christ (God is the center with Christ a doorway).
The majority of JWs only receive salvation based on their hanging around the "anointed", a kind of "grace by association". While they still offer prayers to Jehovah through Jesus, the official doctrine is that most JWs only get salvation by following the teachings of the organization. They only receive salvation, not through Jesus, but from Jehovah through Jesus as passed on through the "anointed".