Who were some of the important early leaders of Indiana and what made them important?

Answer 1

I suppose it depends on your definition of "early." I guess you are talking about statehood, which took place in 1816.

William Henry Harrison (future president) served as Territorial Governor from 1800 to 1812.
http://www.whitehouse.gov/history/presidents/wh9.html
http://en.wikipedia.org/wiki/Battle_of_Tippecanoe

Jonathan Jennings was the first governor of Indiana.
http://www.statelib.lib.in.us/www/ihb/govportraits/jennings.html

Indiana's first two US Senators:
James Noble (1816-1831)
http://bioguide.congress.gov/scripts/biodisplay.pl?index=N000118

Waller Taylor (1816-1825)
http://bioguide.congress.gov/scripts/biodisplay.pl?index=T000102

Indiana Governors
http://www.statelib.lib.in.us/www/ihb/govportraits/govlist.html

Indiana Senators
http://www.senate.gov/pagelayout/senators/one_item_and_teasers/indiana.htm
Congressional biography
http://bioguide.congress.gov/biosearch/biosearch.asp

Tecumseh was a Native American leader who fought in Ohio and Indiana during the early part of the 19th century.
http://www.heidelberg.edu/FallenTimbers/FTbio-Tecumseh.html