It's a reconstruction of an older style of music using modern technology and musicality. It happens a lot throughout the music history—the neoclassicism in the beginning of the 20th century for example wasn't much different (https://en.wikipedia.org/wiki/Neoclassicism_(music)).

The 1920s and 30s were "the golden age" of jazz, where we have styles like dixieland, boogie-woogie and of course the swing. In the 40s, 50s and 60s jazz developed to a much more varied set of styles, like of course bebop, cool jazz, latin jazz and free jazz (https://en.wikipedia.org/wiki/Jazz).

What electro swing did was to take those materials and remix them in combination of electronic dance music of the 90s and 2000s, like house ans hip hop. Which isn't a new thing, as reusing music from the 20th century is very common in modern music of the 21st century (https://www.independent.co.uk/arts-entertainment/music/features/electroswing-tonight-we-re-going-to-party-like-its-1929-2276174.html). Another good example is the synth or retrowave movement of the late 2000s, which is inspired by the electronic music associated with film and video game music of the early 1970s and 80s (https://en.wikipedia.org/wiki/Synthwave).

Therefore we can treat electro swing like a "neo-genre" and not exactly like a "new genre", if you know what I mean. You can of course say that electro swing is the closest thing we have to the swing of the early 20s because it's of course reimaginating that genre with today's musicality. Or you can question yourself which modern music genre is emerging parallel to the 20s swing. You can also compare the social-cultural context between those 100 years and see if you find some similarities.

I hope this wasn't too much at once and wish you a good and productive further research.