Seen here is a glimpse at the kind of world and wildlife that the first emigres from Northern Asia to the Americas faced. Including an illustration of a giant sloth. That would be something to see, yes. I think once you went from one hemisphere to another, the kind of animals you saw would be vastly different. It makes me wonder what they thought about it.
There's been some controveyersy over whether the proto-Americans caused the extinction of the continent's megafauna. They were proficient hunters, yes. Probably not enough to cause mass extinctions, though. Not without the geological and climactic changes that were also going on.