One of Negan's key identifiers during his days as The Walking Dead's primary antagonist was a barbed wire-covered baseball bat, which he named Lucille after his deceased wife. The modified bat was entirely an invention of the zombie apocalypse, necessary for the antagonistic role Negan played to zombies and humans alike amidst societal collapse. "Here's Negan" reveals that, by contrast, his signature leather jacket was a character trait of his dating back to pre-zombie apocalypse days.
In the episode, Negan is shown obtaining his jacket in a series of flashbacks to some of his formative moments, both pre- and immediately post-apocalypse. Rather than acquiring the jacket through illicit means as he might be compelled to do later on, Negan simply purchases the jacket from a store for $600.
That said, his wife Lucille (who's still alive at that point) attempts to return the jacket in light of Negan's splurge coming in the wake of losing a job. Post-apocalypse, however, she reveals that she never ended up returning the jacket, and gives it back to Negan as a gift. Thus, Negan's jacket remains not just an identifier of his character, but also a connection to his dead wife that persists into The Walking Dead's present.
