. Are we in agreement that it would be dramatic if we only included humanity exactly like us? I

Yes, because there are times in the history of humanity where we got close to being wiped out (the Toba event being possibly the best documented).

I'd like a second opinion from others if a specific anthropic principle is allowed, because it seems reasonable to me.

I'd be very curious if anyone else agrees with you there. I don't understand the basis for such a specific reference class, since every intelligent species that thinks about MWI will be in the same position.