Polish-Lithuanian commonwealth was the first parliamentary monarchy in Europe, most likely in the world too, from 1569.
Kings were elected,
No, kings were elected since 1370.
First "election" was made in 1177.
Since 1573 it was full democratic election but the rules was made earlier.
Earlier choice was making by small group of people.
Parlamentary monarchy begin about 1493/1505.
acting more like presidents than sovereign rulers.
Yea! something like that. It was a life-time president.
And even not as president in presidential system, but like in parlamentary system.
Number 2 (nobility-limited democracy) is a kind of oligarchy and I don't see how it is a contribution to the outside world anyway.
No, it wasn't limited democracy!
Every member of nation could vote - elect reprezentatives to parlament and elect the king.
Did British had something like that in times of Tudors or before? I deeply dout.
But you must remember that nation = nobles.
Others inhabitants weren't from the same nation,
and weren't the citizens of the polish countries.
So, it was 100% democracy. Unfortunately.
O! It seems to explain many things...
More recently (21st century) also Lucjan Łągiewka, his EPAR technology and other inventions (Google it).
Yea, this is the cool guy!
Something like polish Tesla.