It's a standard Catholic one-liner, in response to someone whining "But I assumed...." that "the only person who got anywhere by assumption was Mary".

I guess it's the "take-up" meaning. Taken body and soul up into heaven, that sort of thing. I bet it was named in Latin first (as so many church things are) and then just borrowed straight into English. So the question is, do the subtleties of the definition of the Latin form of assume include literally taking up? Any Latin-types wanna answer that?