Actually, remember that there have been literally HUNDREDS of ships named "Enterprise" throughout REAL history... certainly, more will follow. If you just accept the really major, significant ones, there are several sailing vessels and two aircraft carriers. I mentally "retcon" that scene in TMP by assuming that those pictures are actually display screens, and that ALL ships named Enterprise are up there, cycling through. Perhaps they're subdivided by historical period... meaning that the sailing vessels will cycle through the first pane, powered naval vessels through the second, the early Earth space vessels in the third, the early FTL ships in the fourth, and the "Federation Era" in the fifth. So, the only real question there is which of the two categories you'd put the NX-01 under, the fourth or the fifth display screen?
Not that I ever gave it too much thought to begin with, but that has got to be the most ingenious rationale I've ever read! Sincerely, Bill