Even by Led Zeppelin's first album though, Page had experience in other bands plus a lot of time in studios as a session player, so while he clearly has talent I still think that his experience and dedication are what allowed him to become truly great.
Um...no.
I can only speak as a person with 26 years of studio experience writing, arranging, producing, and recording professionally, and that alone requires lots of dedication, and even a little talent. I've also worked with plenty of dedicated musicians who had some talent, and have guest lectured on this stuff at University level. I know lots of dedicated, experienced people with some level of talent.
None of them, including me, have proven your theory correct. Quite the opposite. The ones I know with big talent are the ones who go on to do great things. The rest get to a certain level, and that's that.
Very few folks have a talent for part writing - this is why Page got session calls in the first place, there are plenty of good players who can't create a solo melody to save their lives. Very few folks make great producers; at the top level you see the same names over and over, and there's a reason for that; it's because they're more talented and better at their jobs.
Page only had a few years' experience under his belt, he was a kid, relatively speaking, when he did the Zep records.
I've seen a lot of hard working, dedicated, experienced people come and go. Talent is the distinguishing factor. The ones who have it do things a little differently from the rest of us, the people with a modicum of talent who work hard for a long time, the
lumpenproletariat of the world of music.
Talent is something people are born with, it's not learned. And there is great talent, and smaller talent, and the differences between them are easily observable.
Certainly talent can be brought out and informed by experience, it can be nurtured, but you either have it or you don't, and if you don't, you could be in the studio for a million years and not make a record as good as Zep's stuff
that is still being listened to after nearly 50 (!) years.
In the introduction to Rimsky-Korsakov's classic book on orchestration, he made the observation that he could teach you everything you need to know about orchestration (in addition to being a great composer and military officer, Korsakov taught in his later years at a university) but he could not teach you to be a composer, because that ability is something that can't be taught. That's as true now as it was in the 1890s when the work was published.