As you age, the relevance of most manga begins to fall off your scope considerably. The repetition of the “Hero’s Journey” template dulls the interest of ageing readership. The typical story of good versus evil, friendship and love, seems utterly nonsensical for your current mental age. Does it imply that you are too old for manga?
Yes, and no.
Shounen or shoujo manga, as indicative from it’s genre is targeted towards teenage boys and girls. As such, the content would mostly seem naive and unrealistic. But fret not, there are manga tailored for the matured audiences as well. Seinen (mature male) or Jousei (mature female) genres are such that are written for the matured audiences.
Seinen manga usually revolves around more on historical and political sub-genres, usually a topic highly of interest towards the matured males. An in depth psychological element persists as well, with a much more realistic approach throughout the storyline.
Jousei manga shares the same elements, however it focuses more towards the realistic variations of love; introducing psychological elements. Offshoot branches of Jousei which revolves on historical and/or political sub-genres exists as well, but usually it is highly defined by a main female protagonist with a high tendency towards a female’s state of mind.