Is it normal to be able to sing spanish songs without speaking spanish

Volare is Italian.

Yes it is. I like Swedish music and I sing along with that, although I only speak a little of it.

I sometimes do the same with German

If you don't know any Spanish whatsoever, you are probably singing "bradalalala la bamba" instead of "para bailar la bamba" etc but yes it's normal to find songs like that catchy and burst into a fit of nonsensical song.

Selena did it why not you.

Probably you have the natural talent of a good memory and a good phonology, totally normal

Yes

Yes it is. You can learn the sounds. Try singing Gaelic though its freaking difficult.

Pretty sure you're just memorising syllables. You may be messing up the pronunciation, I don't know, but if it's singing it's just for fun anyways!

I can sing tunak tunak tun and I dont know any Polynesian.

All you have to do is memorize the lyrics, en español o no en español.