I don't know if this counts as head canon because I do not necessarily believe it, but, could season 2 of TNG be considered a reboot of the series? I think everything of season 1 other than the pilot episode and Tasha Yar were totally ignored, and around season 2 is when things started to cement. The Data of season 1 who used sly emotions and was comfortable with human language is gone, and the characters have developed on the whole. There is a lot about season one that feels inconsistent with what followed.