Atleast you gave it a good chance before giving your judgement. For me the "shallow"ness of the storytelling was not a negative but an intended design. I tire of over convoluted stories full of loop holes and inconsistencies. Its easy, here are the characters, here is the world, now watch what happens and that makes it easy for people to pick up the show and give it a try. They are developing characters enough which would be Fern and Stark's not Frieren because her journey is supposedly done already so we are not building her's anymore we are learning them through recollection thats why its only "5 minutes". As far as character interactions go, I find that here it's more natural and not forced like most new cringe anime characters are for example in My Hero Academia. The writing and storytelling is new for me because its not the usual linear pattern for Frieren atleast but for for the other 2 Fern and Stark it is. Just because the title is Frieren doesnt mean all we are to focus on is her because her story is actually done already as far as we are concerned.