Challenges from Big Boy

Big Boy notices everything.
He notices when I change the color of my toenail polish. He notices when I'm wearing my heart pajama bottoms and a blue tank top rather than the heart pajama bottoms and the proper heart pajama top. He notices when I put my hair up (and it's driven him to tantrums). He notices if I switch purses. He notices if I've put on mascara.
So I should not have been surprised this morning when we were watching Dora and he said, "Mommy, Dora is brown. Why Dora's brown, Mommy?"
But I WAS surprised!
I said, "Well, some people just have darker skin and some people have lighter skin."
He said, "We have lighter skin, Mommy. I wish I was brown like Dora."
"Well," I said, "You just have lighter skin and that's okay."
He said, "She has brown eyes. I wish I had brown eyes like Dora. You have green eyes, Mommy. I have blue eyes. I wish I had brown eyes like Dora."
"Well," I said, "Your eyes can see and that's important. It doesn't matter what color they are."
WHAT DO YOU SAY?
I'm finding, increasingly, that motherhood is requiring me to think a lot faster than I anticipated, and to question what I say more frequently.
I want to give Big Boy straight answers, but I don't want to say too much so he doesn't understand. But geez, he sure comes up with some challenging ones!