Greetings!
(FOREWORD: Apologies for the great amount of exposition on this post, but I wanted to be as through as possible on my explanation in order to get an as enlightening answer as possible. I would humbly like to submit that if you cannot be bothered to read such a long-ish post, then you can simply look at the title of the thread and contribute to it (if it pleases you to do so). Thank you for your time in advance).

I have purchased the base game a few years ago, and eventually also bought the Morrowind and Summerset DLC's on time.
Back then (before the Morrowind & Summerset DLC's) I had started an Imperial Dragonknight character and played to the end of the prison/dungeon in Coldharbour, but I did not really follow through and stopped playing (no particular reason, just real life and the typical lack of time etcetera).
A few years passed and now I am back to the game.
After checking out a few things I went back to my old Imperial DK in Coldharbour (^^ at the end of the prison/dungeon level whatchamacallit), and there in front of me was a so called; ''Hooded Figure''.
Initially; I did not immediately want to talk to this Hooded Figure (that was stationed right in front of me), because I wanted to get a hang of the controls of the game and checking out the basic menus (inventory, etc).
After a while, I logged back into the game and the Hooded Figure was gone. But thankfully the other NPC that was required to finish the Coldharbour tutorial was still there (the Nord Chick? that swaps places with the Prophet in the ethereal prison thingy).

Since then, it's all gone well (well besides the vanishing of the elusive Hooded Figure) and now I am back on board a ship in the '' real world'' of ESO with the blue ghost-ish figure of the Prophet in front of me, ready to chat.

But I cannot help but be curious, and slightly worried.
I know that Morrowind had added a new tutorial zone (even though I never played it myself). And I also know that the latest DLC (Summerset) also has added a new tutorial zone (that I have only recently played through with a test-run character).

So.. by starting the game with my old character from the old tutorial-zone (Coldharbour), am I missing anything?
Am I missing any story / sidestory (quests etc) content that I cannot do later on, I mean not for the sake of levelling, but for the sake of roleplaying and experiencing the content for myself?
Can I either do the Morrowind and/or Summerset tutorials with my current character in the future?
*Will I get to talk to the Hooded Figure again and did I miss anything significant (important tidbits about the story etc) by not having the chance to talk to her/him?
Basically as the title implies; am I missing something by starting the game now from the old tutorial area? If it's a bad idea to do so (for some reason) then perhaps you would recommend that I start up a new character?
(PS! The reason I went through all this, uh, trouble to pick-up my old character and write this post on the forums is because I had spent a lot of time visually customizing my old DK, and when I tried this time, the results weren't satisfactory to me. Then there is the good old character delete limit as we all know, so I decided to give my-old-dusty-character another shot, unless it causes some unforseen bugs&/problems etcetera).
Thank you again for your time.
Cheers!