So is Hell really forever?

If I died without repenting and went to hell, then Can’t I just go to heaven just by repenting in hell?

What happened to Adam & Eve who didn't repent nor believed in Jesus Christ because he wasn't born yet? Luke 16:19-3 said Adam and Eve are in purgatory aka Abraham's bosom. But Purgatory is in Hell. correct?

1 Peter 3:18-20 and 1 Peter 4:6 said, Jesus went to hell, and then ascended back to Earth and then ascended to heaven. How do you explain that?