The preface has no specific legal weight because no specific power is delegated by the Constitution to the feds in the preface. The preface is only a statement of intent, useful when deciding things like what’s “proper” (from the “Necessary and Proper” clause for instance), things like that.
The legal weight is the ABSENCE of an enumerated power delegated to Congress by the Constitution in Article I.
The feds are 80%+ unconstitutional but you gotta start somewhere and overturning federal interference with state anti-abortion laws would be a great place to start.
It’s a Preamble.
The Preamble is a statement of the Constitution’s Natural Law foundation.