Were all four members really equal and essential?

You keep bumping into things.

True.

Freddie was a bit more important than the others, Brian the second most important member. Roger and John were also important, but one of them could have been replaced by some other skilled musician, and the band may still have gone on to be successful. Queen wouldn't have been the same of course, but still successful.

I think it's a 35/30/20/15 (F/B/R/J) split in importance or something like that. Maybe a tad more even, but there's no way that they just by coincidence happened to be exactly equal and contribute by the exact same amount to the bands success. It's a nice thought, but not realistic IMO.

This is all from a musical point of view. Maybe John was very important in handling their economy etc. etc. and it'd all have been impossible without him.

I also agree that much of Jazz belongs to their absolute best work. Bicycle Race is such an understated work of art for example. The problem is that there are some absolute stinkers by Roger on there, and the production kinda ruins some of the ballads (Jealousy, Leaving Home).

"but one of them could have been replaced by some other skilled musician,"

Fuck off. People put John '4th' but he wrote Queen's biggest ever hit and thus made them the biggest band in the world. Did it lead to Hot Space, the worst album? Maybe, but they all played an intrinsic part of their history. "Were all four members really equal and essential?".. Yes.. to being Queen, if anyone else was part of the four then it wouldn't be the Queen we all know.

I think that only the combination of those 4 individuals makes the sound of Queen we all love.

Take a look at Freddie solo: well... not that imposing. (Ok, Barcelona is quite marvelous, thanks mostly to Mike Moran and the brilliance of the idea to combine opera and pop/rock.)

Roger solo? The Cross is ok, but not that special. And his solo-albums are solid, but nothing to be enthusiastic about.

Brian solo? I think that he wants to sound like Queen the most, but in the end you think, I still miss something. At least, I did.

John never did any serious solo stuff (Except Man in the shadows, which is brilliant, by the way), but you have to judge him only in his Queen-work.

So the four of them individual... I honestly think that they won't had success on their own. But together is a complete different story:

You have the voice, the mystic lyrics, the out-of-the-box-ideas and vision of Freddie, the bombastic guitar layers and romantic melodies of Brian, the groove and rock&roll of Roger with his high-singing notes and the subtlety and flexibility of Johns bass-lines (especially the higher parts of his playing, wow, incomparably!) and there you have it! It's a kind of magic....

I think nobody's denied that Queen as we know it needed all four of them (plus engineers, producers, roadies, etc., had one of them changed, it'd be a different story however slightly). That's crystal clear. So half of the topic is answered there: were they all essential? Yes, of course.

However ... were the four of them *equal*? Now that's a different story.