Thank you for playing! Great that you explored some of the remnants. Did you watch the crystal? It tells you when a gate is near.
More content is being prepared. When you were teleported back you obviously (and unknowingly) activated the personal portal rune which brings you back to the tower of your mentor. It is described in the dialogue, a note on the wall and in the help page.
I am glad that you had some fun in exploring the game.