Take a gander at this photo of a Chevy lower end viewed from the bottom... You are incorrect in one of your assumptions... that the cylinders are not offset. They are in fact offset by about an inch.
Notice how each rod journal (that's the word you're looking for) holds two rods. The first thing you see on the left is the front of the engine, the crank snout. Then you see the oil pan rail in light grey, then you see the first main cap. This is what holds the crank to the block via the main journals. The next thing you see is the first counterweight on the crank. This particular chevy has been balanced by drilling material out of the counterweight. Take a look at the two rods just to the right of the second main cap. The left rod on this journal goes to the far bank, and the right rod on this journal goes to the near bank.
The reason they don't need to be offset is because the cylinders
are offset in the block. I tried to find a representative photo of an engine block, but none showed the proper angle. Take a look at this intake from Edelbrock. It gives you an idea of how the two banks of cylinders are offset by how the intake ports are offset.
The driver's side bank of cylinders (the odd numbers on most cars) are always set forward by about an inch or inch-and-a-half. That is how the rods can share journals without being offset.