Some of the skin variants (especially the themed ones) seem like characters from alternate universes mixed in with the timestream entanglement but aren't important figures in the story. I see some of them as different universes and others as events from the more important universes, for example, the immortal dragon theme seems like an ancient Chinese universe where those characters lived and do superhero stuff in ancient times (like the what if episodes in medieval times or during the wild western period). Whereas something like Punk Revolution and 60th anniversary take place in the 2099 universe and the present day New York universe respectively, where the Hulk of that universe is Punk Hulk. BTW its up to you if you want to add the skins but I doubt they will bring in these small themes (immortal dragon etc.) into the lore. But skins related to the story (like the blood shield skin) and the original skins, I personally think connect to the story/lore even though the descriptions are quite vague.