You might be looking at the data wrong. The chart at top is how many OW2 premium skins that hero has been given per month since launch. It does not include ordinary stuff, nor anything from OW1. The filter includes only (Shop, Mythic, Battle Pass).
For any premium skin since OW1, see below for the top 10. This would be everything from OW2 plus holidays and such from OW1 but does not include the basic skins each hero gets. The filter is everything except (Overwatch, eSports, OW League).
Tracer jumps up, but still, Mercy, Widow, Ana are near the top. But yea, suddenly in OW2, Tracer has been quickly replaced with Kiriko, and most original OW1 heroes are getting skins much less frequently than the favored waifus.
| Hero | Age | Skins | Months/Skin |
|---|---|---|---|
| Mercy | 101 | 27 | 3.7 |
| Widow | 101 | 26 | 3.8 |
| Tracer | 101 | 25 | 4 |
| Ana | 99 | 24 | 4.1 |
| Genji | 101 | 24 | 4.2 |
| Rein | 101 | 23 | 4.3 |
| Sombra | 95 | 22 | 4.3 |
| Reaper | 101 | 22 | 4.5 |
| Pharah | 101 | 22 | 4.5 |
| McCree | 101 | 22 | 4.5 |