Following the "Main quest" ? (possible spoilers)

[FM Helldiver Radio]

I was following something I thought it would be the main quest.

I did stormveil castle and was at the roundtable hold. Talked to anybody and they told me to seek the elden ring.
Then there was lurnia and the raya lucaria. I killed renala and found Miriel in his cathedral.
Later there was the caria manor and the three sisters where I met ranni.
Did the river of Siofra and Caelid, where I went for Radahn and am now on my way to Nokron...

By accident I read a post that said Ranni, Radahn, etc. are optional...
So I think I´ve lost the main quest somewhere.
To be honest to myself I have to admit, I don´t know what I´m doing since I left Stormveil castle. I was just running around visiting all cool looking locations.
There are NPCs and Quests that go on.

Thats fun and I really enjoy the game, but I have no idea where the main quest is and where I lost it. In the beginnig I was told to follow the "pointers" at the sites of grace but they don´t seam to be any help as they just point to the nearest area boss even if it has nothing to do with the main story.

I don´t want to get tooooo many spoilers, but just a little hint.
Is there some NPC somewere I have to talk to? Some cutscene I have to trigger? What would have been the "next step" after leaving stormeveil castle?

[vamirez]

You cannot "lose" the main quest. The game is very open as in the steps to complete the main quest are not very many, and you have different options for how to obtain the great runes. As has been laid out by commenters above. However, imo the main part of the game is to explore and do everything and enjoy yourself doing that. Also note that if you try to explore everything, your level will generally be at least sufficient for the challenges that come (no farming needed).