"Too Soon" is a thing.
People born after are grown ups. So, too soon is over.
Is it offensive to market anything with ww2 imagery? Or all the murder death killing games with bubbly graphics and real life guns players can shoot with?
It is not the right question to ask, if it is offensive. It obviously is, as it would be with a lot of topics. Most things are offensive to someone.
Is it allowed or rather forbidden? No, of course not. How could it be forbidden. There is this whole free speech thingy that also applies to games.
The real question is, if it is wise to do so. Some advertisements are intentionally provocative. You do not seem to have a publisher, nor a big game. And probably no marketing budget. So for every view you might get because of the imagery, you might lose another because someone skips it.
My opinion is, the skipping would be the majority.
Of course if your use of the topic is offensive to enough people, Itch might decide to unlist your game. But since there are games currently listed with that topic as a game no less, I doubt that people take the effort to report these.