Unfortunately, circumcision is a particular form of mutilation that transcends cultures.

a lot of mutilation goes back centuries for human history. You can pick up any variety of mutiliation and it's been done, scarrification, penile subincisions, foot binding, skull stretching, i can keep going.

Just because it's historically common and pervasive doesn't mean we should consider it to be normal. The aztecs commited human sacrifice, and we think capital punishment is bad enough that we need to hide it away from the general public and make it "sterile" which in reality means using a completely botched medical injection process.

also what culture "should be" does not determine what it is now, i'm not sure the legality of naked baby photos to begin with tbh, i'm pretty sure they're still considered to be CP, unless legally stated otherwise somewhere. They wouldn't count as CSAM i think, since there's not abuse going on, but arguably it might count as CP still.