Jehovah's Witnesses are one of the groups that developed from the Second Great Awakening era of American religious history.
The Second Great Awakening developed among uneducated or unlettered Christian preachers, with a great hatred for the Papacy. As a shared earmark, almost all the movements that arose from this era claimed to be either restorations of the Church established by Christ or the replacement for the Church, especially the Roman Catholic Church which these groups believed was false, even demonic. The Bible Students movement (which came from this American phenomenon and splintered into the Jehovah's Witnesses) saw things and themselves no differently.
The Witnesses believe that during the final generation of human existence, God will introduce them as the restoration of true Christianity that would supply those who accept this restored movement with salvific entry into the coming Kingdom which would replace the current world at any moment. Many practices of Christianity of the past, including the use of the English word "church" was rejected by the Witness leaders. Seeing themselves as the restorers of original Christianity, they felt they had the authority to make such "changes." Switching the "ownership" of the congregation from Jesus to "Jehovah" was quite easy for a group that sees themselves chosen by God to make such changes.
Those other groups, the SDA and the LDS, made similar claims and "changes" like the Witnesses. Believing that we are in the last of latter days of human existence, they each saw themselves as the assigned "restorers" of "true Christianity" and as such changed whatever they felt needed to be "adjusted" as part of their "assignment."
All three groups share another earmark, that of claiming the right to deny anything from history or even Scripture on the grounds that it is their job to 'set matters right' in these final days.