Thread:SeanWheeler/@comment-26095292-20171215215954/@comment-2112031-20171220221229

Mutants could have existed in small numbers prior to modern day, their growing numbers could have coincided with the Inhuman Outbreak, causing people to, as you pointed out, mistake them for Inhumans.

The origin of the X-Men in the MCU could be similar to that of the Ultimate X-Men. In that version, Professor X and Magneto initially built a home for the growing mutant population in the Savage Land. Eventually, the two had a falling out and Xavier fled from the Savage Land back to the United States, where he founded his School for Gifted Youngsters and subsequently created the X-Men. That sounds like it would make a pretty decent first movie.