They only added Hell in the Middle Ages (even the name comes from the Vikings). It’s like when comics make the canon needlessly complicated in later years because they have to keep going no matter what.
The first 500 years of the cult had already fractured into a few different forks and had very different ideas about afterlife already before Rome picked it up and popularized it as official religion.
At least that's my understanding.
Anyways, the actual history of religions should make anyone atheist.
I've been learning a lot about biblical history and early Christianity lately. To be clear: as a layperson. Ie I've been listening to podcasts by biblical scholars, and reading Wikipedia articles. I'm not an expert but I'm an interested lay person. I've been doing this as a person that doesn't believe in the supernatural, because I'm interested in history and sociology, I haven't been learning about hell specifically but more the context influence of Early Christianity.
Early Judaism understood the afterlife to be a sort of sleep/slumber/torpor.
Greek concepts of hades had an influence on early Christianity.
The Book of Revelation was kinda like a revenge fantasy for early Christians experiencing persecution by the Greco-Roman empire.
The lake of fire was not for human souls.
There's also something about souls being fed into an eternal furnace, but the furnace is consuming the souls so the souls are destroyed through incineration, not eternally tormented.
I know a lot of current hell imagery is drawn from Dante's Inferno which is medieval I think, but I haven't really gotten that far in my learning about Christianity.
The Book of Revelation was kinda like a revenge fantasy for early Christians experiencing persecution by the Greco-Roman empire.
The lake of fire was not for human souls.
While Revelation isn't exactly the best source as you say, it still has this part regarding a lake of fire:
But the cowardly, the unbelieving, the vile, the murderers, the sexually immoral, those who practice magic arts, the idolaters and all liars—they will be consigned to the fiery lake of burning sulfur. This is the second death.