There are many aspects of Christianity today that would be unrecognizable to early Christians, but belief in hell probably isn’t.

There are the usual caveats about when passages of the Bible were actually written - the canonical new testament wasn’t solidified until long after when Jesus was supposed to have lived, and it’s understood even among Christian scholars that books attributed to one author (like the gospels) actually draw from multiple earlier texts.

All that said, in Luke Jesus tells a parable about a rich man in hell asking a poor man in heaven to go and warn his friends so they don’t also end up in hell.