You are right...but there is a bit more to the story. The 747 program was launched on the back of a failed bid to design a cargo airplane for the military, the Lockheed C5 Galaxy was the winner. This failed military transport design was then picked up and was the basis from which the 747 team started work. This is the reason that the cockpit is on the upper deck, as opposed to the lower deck as in the A380, one of the design requirements for the military transport was a front loading bay and a cockpit on the lower level would not have allowed that.

You are right that the 747 program definitely considered both freight and passenger versions throughout their design process, but that was pretty much assured from the start given that the plane they designed had its roots in cargo.