"Hell" is simply our own grave...Romans 6;23 states that our own death is full payment, like wages, for things we have done wrong...further, Jesus' death fully paid for sin we have inherited...Babies do die, so they are sinners,,,having inherited sin...and they have done nothing wrong.
Genesis 2; 16,17
In the Bible, Hell is Hades...and it says...
(Revelation 20:14) And death and Ha′des were hurled into the lake of fire. This means the second death, the lake of fire.
No death = no Hades = no graves...
i.e. Hades/ Hell = the grave.
(Revelation 21:4) And he will wipe out every tear from their eyes, and death will be no more, neither will mourning nor outcry nor pain be anymore. The former things have passed away.”