This provision dates to 1776. The present wording dates to the Constitution of 1790.
The concluding phrase in the 1776 Constitution was "pursuing and obtaining happiness and safety."
The 1790 Constitution also substituted the word "indefeasible" for the word "inalienable." "Indefeasible" means that something cannot be forfeited or taken away. "Inalienable" means that something can't be transferred or given away.