I choose to believe this, because otherwise it's extremely unlikely that humanoids with identical features evolved both separately and independently, several galaxies away from each other with no interaction at all....Yet they look and behave the same.

It would also explain why Galactic Basic sounds identical to a mix of American and Transatlantic English. Star Wars is just a dramatized retelling of alien rebels standing up to their alien government, with the rebels being portrayed as English-speaking humans so that Westerners on planet Earth will sympathize with their cause.

I think the Bene Gesserit still had to be impregnated. I'm not that deep into the lore but I doubt they could just will themselves into pregnancy.