SOLVED. Sci-fi book with space travel & group investigating ruins of an alien civilization [s]

[Mandy]

I read this book in the mid-90s, and it started with a scientific group looking for the remnants of an alien civilization on a planet, maybe Mars. One of the scientists sabotages the oxygen mix in the camp and kills everyone else, then goes off on his own to investigate the planet.

Meanwhile, about 4-5 other people (maybe all human, maybe including some aliens) come to the same planet for different reasons. One of them is basically a space trucker, piloting a cargo ship. The group finds the ruins of an alien civilization and investigates it. It's filled with a bunch of different environments and creatures. I think the aliens were triangular-shaped, not human-looking at all.

Spoilers: The group finds out that the aliens created humans and/or Earth's entire ecology, but the space trucker created the aliens (so he's God, apparently) and has chosen to forget all of that in order to live a simpler, happier life because he was lonely being God.
In the end, God sends all of the characters off to a reward or punishment perfectly fitted to each character. The one who killed his fellow scientists becomes a herd animal on the planet but still has his mind and memories and so he's totally aware of being killed & eaten by a predator, but can't do anything about it. After being eaten once, he's reincarnated as another herd animal and runs off a cliff to escape being eaten again. He wakes up yet again, and finally realizes he's going to do this a number of times equal to the people he killed at the beginning.
Another character, who was a slave of some sort (prostitute or sexually neutered, I can't remember which) is reincarnated as a successful business-person on a planet of hermaphrodites.
God goes back to being a space trucker.

[Sophie]

God goes back to being a space trucker.

I don't know what this book is, but now I kind of want to read it.

[Barbara]

"God goes back to being a space trucker."

Best line I've read in a long time.

[Bryan457]

I think it might be

[Mandy]

That's it! Thank you so much!