Many religions view dedication to God as a promise to do his will. Child dedications for example do not assume salvation but a promise to bring that child up "in the faith". Hannah was a barren wife who promised to dedicate her child to God if He would give her a son (1 Samuel 1:11). Luke 2:22 begins the account of Mary and Joseph taking Jesus to the temple after forty days in order to dedicate Him to the Lord. This was slightly more involved since it involved a sacrifice, but once again this ceremony did not indicate any level of salvation.
JWs view Baptism as the public display of the dedication they have previously made to serve Jehovah.