Who wants to summarize American history (north and/or south) from the first record of human activity until 1492?

I'm not sure any single human could possibly do this and certainly not within a reasonable character limit. There's simply too much history in the Americas for any summary to be anything but incomplete. This misunderstanding of scale is an issue that several of my European friends have. Personally, I suspect it's because the modern American nations-states are enormous compared to the sizes of nations they're familiar with and this presents the illusion of homogeneity. In reality, the North American continent alone is so wide that if one edge were placed on London, the other would cover Bangladesh. There would be enough land left over to cover all of Europe, India, and all of Western Asia. Large portions of Central and Eastern Asia would be covered as well.

That's just North America too! South America on its own could cover the distance between Beijing and Jerusalem.

Within these incomprehensibly large areas we call the "Americas", humans have a long history. Current research indicates that humans originally migrated to the Americas sometime before ~20,000 BP (pre-clovis hypotheses), but it's widely agreed that the bulk of human migrations occurred after this period, approximately 18,000BP. In both cases, humans migrated over the Bering land bridge to arrive in what is now Alaska. The dominant hypothesis for initial settlers suggests that the first people moved quickly down the Pacific coast. Artifacts from the San Dieguito peoples of Sonoran desert suggest that by 10,000 years ago, humans were well established in Northern Mexico while archaeological evidence in the Central highlands suggest rather earlier dates. Somewhat contentiously, the Monte Verde site in Chile implies a pre-clovis culture that migrated down the coast well before either of the former two.

20,000+ years of history across landmasses equal in area to Europe, Africa, and Australia combined make for a history that's difficult to summarize.

As /u/AlotofReading said, covering 20,000+ years of history over such a large area is impossible for single reddit post. It took me 6+ posts to give a crash course in the history of the Ohio Valley through this lengthy time period. Since that questions is over a year old, feel free to ask any follow up questions you may have here.

In Europe there's a Eurocentric kind of history teaching and American history only starts at 1492 with Columbus.

As a Norwegian, I can say this is factually incorrect. In addition to Leiv Eriksson, we also learn quite a bit about native history. It is of course going to be a lot less than let's say European history but mostly due to lack of documented history to the same degree as is found elsewhere.