Please recommend me a manga series with MC as a mob character or MC don't wish or like to stand out.

Rokkon Shojo
TeppenMezashiteTondeAruYo
Let justice be done, though the heavens fall

These are mostly comedy/shounen:
Romsen Saga
Mob Psycho 100
The Eminence in Shadow

Onani Master Kurosawa (as to include one with less comedy)

The stockpile manga/manhua MC (manwa female MC) supposedly tries to not stand out so most MC's are initially like that.

There are tons of them but they usually end abruptly or the MC becomes the main focus on ch2 or lose edge after 10 ch.

Kino no Tabi - The Beautiful World (Novel) mc travels around and mostly observes. There are adaptations if you don't like novels

Saiki Kusuo no Ψ Nan mc doesn't want to but he does so badly.

Majin Tantei Nougami Neuro mc is demon detective who forces human girl to front as the detective and poses as fer assistant. Not how well it qualifies but it is hilarious and good.

I'll second mob psycho

Yuujin Chara wa Taihen desu ka?

🙂

A BL twist on this is Zettai BL ni Naru Sekai VS Zettai BL ni Naritakunai Otoko where MC tries to be a generic character and not fall into to common BL tropes, pretty amusing honestly.

✨~* ~ * ~ * ~ * ~ * ~ * ~✨

+a no Tachiichi - I guess this one fits perfectly. For the story itself, imho, it wasn't half bad. But don't expect any huge character development and also ending may feel kinda rushed.