> Its believed that homo sapiens have been around for at least 300,000 years and yet we think almost all of that was entirely without civilization.

Depends what you call civilization. If there was a civilization what happened to it and why did it leave no trace.

> We find fossil records of dinosaurs but we have little to no evidence of what would have been before them, presumably there was an extinction event prior to them as well.

Actually we do have evidence of what came before them, and there were extinction events.

> It seems foolish to think we are the latest incarnation of the only chain of civilization that had ever happened on Earth.

We might not know about previous civilizations (that is the point of the Silurian Hypothesis - a lot of traces will disappear over time) but we have no evidence that there was any previous civilization, or of any sufficiently intelligent animal to build one. The oldest stone tools we have found are only about 3m years old.