You're all forgetting one thing: that Lavos' energy distorts time, creating gates. As such, there would be gates popping up in certain areas and whatnot. Going by this, there are people out there with more than half a brain; somebody would figure out that they could alter time using the gates, and perhaps get thrown into something akin to the middle ages. (Arthurian time, perhaps?) That, and assuming the big rock that killed the dinosaurs was Lavos, then there would most likely be some form of Magic-using humans when we finally came around. Hence, the whole Atlantis thing would occur (mirroring what happened with Zeal) and then, well, you get the idea. I'm just saying that you're all forgetting that Lavos's mere existence would muck up time beyond recognition.
(Come to think of it, I'm getting some pretty wierd fanfic ideas here...)
However, Chrono mechanics aside, we would get our asses kicked by Lavos, hands down.