Is it normal to have the dumbest boyfriend imaginable?

It has been about two and a half years now since I reconnected with my best friend I grew up with in Russia. I had another post about that so I won't go into details. I am not exactly mentally stable but he is nuts. I don't know what to do with him. I have to watch him like a hawk. I love him and we have a great relationship but I just don't know what to do with him!

When we were younger he was more of the big brother protector and I was the itsy bitsy ball of bad luck. I, at 5'9 and 103 pounds, am still on the skinny side, but have graduated to the big brother stage.(protector stage is probably a better term as this is not meant to sound like incest) He is a 5'4, 90 pound pain in the ass.

He isn't stupid, he can read, write and speak Russian, English, Romanian, Turkish, and Polish, same as me. He is good at maths and science. Neither of us had much schooling, I graduated high school and he just had a bit here and there but both of us are smart. I don't know how to word it. He is smart but dumb at the same time. He is book smart but has zero common sense. He doesn't even
read the label to see if he is drinking vinegar or vodka.

He does this shit all the time. He comes out of the shower with shampoo still in his hair. He wears his shirts inside out (Those two may or may not be my fault as I enjoy washing and dressing him. I find it to be adorable)He puts hard boiled eggs in the microwave and heats them up without peeling the shell off and it explodes in there. He has done that three times now! The house reeks with the smell of burnt eggs.

We haven't had sex in a week! A very very very long week. He either forgets that we were about to do something, or has misplaced the lube or whatever else we needed. I asked him if he didn't want to have sex or if we needed to take a break but that turned into a night of him sobbing and me reassuring him that I didn't want anything to change either.

He is an artist and I am a writer but I, the writer, has to make sure that that dumb artist washes his brushes and puts the caps back on his paints so he doesn't ruin them.

I use to think this was cute but it is getting out of control. I am afraid he going to end up hurting himself when I am not there to watch his every move. He could do anything, burn down the house, eat a can full of bulging botulism, stab himself by juggling knives instead of balls. (I know people really do that, but he's not that good though he pleads otherwise)

Is it normal for a person to be this dumb? Is he just so
use to me hovering over him that he doesn't think he has to pay attention? I don't understand it, maybe I am the dumb one and should start drinking vinegar as well.