Earlier quoted context omitted.
Good children's programming often presents characters somewhat older (in affect, if not truly in age, e.g. Big Bird) than the target audience, to act as role models. You don't want a typical 3-year-old to look to a typical 3-year-old as an example for what to aspire to, you want them to look at well-developing 4-, 5-, and 6-year olds. This works well anyway, since children often look up to older kids and are interest…
Sure, but the content of Bluey is not going to understandable to a 2 year old. I would guess 3 is when some basic understanding starts, but 3.5 to be safe. In my experience, below 3.5 or so, more sing song-y and basic repetitious stuff is digestible. Bluey episodes have a plot and lots of dialogue that has to be followed.
My son is 2.5 and he absolutely understands what's happening in cartoons. He will comment on action saying clear things like "daddy he hit him in the head!" And then you have to pause it and actually explain it's not nice and you shouldn't do that. I wish shows clearly aimed at small children didn't have those moments.