Question: Would anyone besides Noah have been saved to eternal life in Heaven between the time of the flood and the time of Abraham?
Noah and his family were the only ones saved to life on Earth just prior to the Flood because they were unsullied by Nephilim seed, but only Almighty God knows how many were marked for “ascension”. There will have been many who are in a state of “salvation” prior to and post the Lord’s Resurrection but are yet to “ascend” to the “Heavenly abode”.
As John 3:13, and Acts 2:34 make clear “ascension” is not possible until “the Lord’s enemies are made His footstool”, which may be close.
See Hebrews 11.