Is it the same protagonist or just the same world with characters from previous games?
Different Protagonists, it's Queen Opala and her family that carry over and develop, the world of II and Origins is the same, I is more of an alternative Earth with fantasy elements while II onward will be it's own fantasy world planet and dimension with magic and fantasy races, II and Origins being set in two different counties on the same world. Again it can be enjoyed without the previous games, since they usually just explain to the player character their background and basic set up anyway.
Personally I'd say play LoQO I as soon as you can, it's the first, the shortest and the "weakest" since it was made with the basics and if you play it first, II and Origins are going to feel like massive improvements, it's a decent RPG and still fun just be aware it was made with zero budget and will last you a solid weekend.
If anything, I'd say you "have to" play LoQO II, mostly because it's huge, a solid RPG game by itself with a lot of content and its story and characters have some set up for Origins, you'll be more invested in Origins after II sets the stage. It will also have the plus of keeping you very busy while Origins is still in development.
