Yeah luffys "as weak" to getting cut as everyone else lol
Plot/narrative
Like yes a bullet can technically take out a normal person but unless plot calls for it it's not gonna happen
Dadan can technically hurt garp enough to make him bleed but garp can obviously take alot more damage and be fine lol
The sea monster could technically kill shanks, mihawk, or zoro i guess but unless it helps push some narrative he wants it's not gonna happen
The first thing we see luffy do is beat it