All this debate is interesting to a point, but I think a lot of it reflects why alignment has little bearing on the game in 5E compared to earlier editions.
I agree wholeheartedly with
@Oofta and
@Bohandas because orcs are not humans.
Now, does that meant they deserve to be killed on sight because they are evil? No. Not IMO. Only an evil character would accept that outlook. Defeated, driven off, imprisoned, killed to protect others or yourself or in defense of your property or land--sure, I can buy that. But just to kill them because they exist? No.
THAT is evil and any PC in my game who acts as such will find their alignment shifting...
I recall when I first began with this group and we ran through the Keep on the Borderlands. The DM explained our goal was to capture and return with prisoners for questioning, with a generous bounty of 25 gp per capture. Well, being a lot of new players, I let them make the decisions and it was a murder hobo-fest for a while. Finally, I stepped in to remind them, "Hey, guys, you know we're supposed to be taking at least some of them alive, remember?" They were like, "Oh, yeah... let's use non-lethal finished on the next ones."
Anyway, I hope people would also notice things like Champion and other NPC-types have
any humanoid listed, not any PC-playable or acceptable race. Want an orc Champion, go for it! Want that orc Champion to be Lawful Good, not an issue because a Champion has
any alignment. Once you break out of the "orc" molds as presented in the MM and other books, you can do anything and still be both following the canon and rules of the game and also satisfying any sensibilities you have.
I have
always allowed any creature to be any alignment, but that is me personally. Are the vast majority of orcs in my games evil? You bet! But occasionally one might be neutral, and work with the party, or even good, and become a lasting ally. Our main DM plays it the same way. It has
nothing to do with real world comparisons or prejudices!
For example, while playing Against the Giants, our half-orc (with STR 19) impressed upon the orcs working for the giants his strength and ferocity in battle. They were given the choice to abandon the giants or be destroyed. They agreed to leave, at which point the PC even offered them a place in our territory as allies if they wish. Some accepted. Most didn't and just fled. Could those who fled kill other people and such someday? Very likely, and if we found them doing so we would defeat or kill them again. They might be executed as prisoners of war, or held as prisoners for labor, or something else.