Magic Jar p. 257 of the Player's Handbook states:
Once you possess a creature's body, you control it. Your game statistics are replaced by the statistics of the creature, though you retain your alignment and your Intelligence, Wisdom, and Charisma scores. You retain the benefit of your own class features. If the target has any class levels, you can't use any of its class features.
Since you gain ability increases and feats (like Elven Accuracy) as part of your class levels, am I correct in assuming you keep them in the new body even if one of them had your ancestry as a prerequisite?