‘Promote the general welfare’ was understood its constitutional sense until the 20th century. Actually, it still is, but it has to be corrupted if the progs are to deliver us into perfect social justice (i.e. perfect tyranny).
The Constitution’s “General Welfare” clause funds Congress to use their "herein granted" powers of legislation to act in the general welfare of the people. It is not an additional legislative power.
Madison in Federalist No. 45: The powers delegated by the proposed Constitution to the federal government are few and defined. Those which are to remain in the State governments are numerous and indefinite.
Until the 20th century, the meaning of the word “is” was understood as well.