The history of Thanksgiving Day starts with much suffering (starvation and sickness) by the early New England Pilgrams.
Then they finally had a bountiful harvest assisted by helpful Indians. The grateful Pilgrams declared a three-day feast to thank God; which they celebrated with their Indian friends.
Thanksgiving is a day of giving thanks for all of our blessings not just food. Even though it has its roots with religious Pilgrams, it is also celebrated in a secular manner as well. It is a great American holiday.