You'd like:
Player Who Returned 10,000 Years Later < exactly what you're asking for
Helmut < he's mostly strong from the start, but he's still young and has some growing left to do (like the beginning after the end) it's more emotional growth than physical, but he can get overpowered by very strong adults occasionally.
I'm not that kind of talent < the reverse of what you're asking for. Everyone knows he's strong, MC does NOT believe he's strong. I think you'd like it anyways. Still an OP from the start story.
Got you, these are BL:
Death Delayed for a Short Time Because of the Will (Yaoi) < obviously. This one is kinda popular, if you haven't yet, check it out. Exactly this plot. Hunterverse
The Hunter Wants to Live Quietly < another hunterverse.
Honbul : Flame of the Soul (Yaoi) < shamen characters. MC likes to keep a low profile.
Kill My Love (Yaoi) < MC is an Ex, famous assassin.
**More NonBL I found include:**
Dungeon Odyss < trust me on this one. Clan building, but MC is strong from the start. Really cool world.
S-Class Hunter Heals with Monsters < dude just decides to live in the wilderness and stay low-key. Strong from the start.

Wait can someone recommend similar stories with OP characters that is hidden or only known by smaller percentage of people other than:
Mercenary enrollment
Star-Fostered Swordmaster
The return of 8th magician
The beginning after the end
I don't want them to be very weak then strong i would prefer if they were strong from the beginning