This is a big question, and but yes - lots is known about life on the North American continent before European colonisation - we have a whole section of our FAQ about it! And the stuff in the FAQ is very much the tip of the iceberg because we have some great contributors well versed in this topic area (check out the user profiles of the awesome /u/snapshot52, the marvellous /u/rioabajo and the great /u/400-rabbits for many more fascinating answers on this topic area).

Additionally, there are several books in our booklist on the North Americas which relate to this topic, if you're keen to investigate at much greater detail than you'd get in an answer here (the booklist suggests that the book 1491 by Charles Mann is a very good starting point, for example.)