Super Mario World begins at Yoshi's Island, where we have two levels at the start.

At the left of the Yoshi's House, we have Yoshi's Island 1. And to the right, we have Yoshi's Island 2.

So, as you can see, the right path is the one that takes Mario to the first castle, and the road to Donut Plains, and the rest of the journey. So, a lot of people, me included, think of the following level as the first in the game:

However...

According to the map, this is actually Yoshi's Island 2. So, it's the second level. The real first level is the one on the left path, Yoshi's Island 1.

But...

If you take the left path you'll end up at Yellow Switch Palace, and this road takes nowhere.

I'm confused. So, for you, which one of those levels can be considered the true first step on Super Mario World?

I usually went with Yoshi's Island 2. For some reason I always thought it was supposed to be that way despite the name, because it's on the right side of the map.

Wanting always to access the Special World eventually, I've typically gone with Yoshi's Island 1 on the left first to reach the Yellow Switch Palace.

I don't remember if you need the yellow switch to advance in the game at some point?

But when you just start out the game you don't really know where either road will end up taking you, so I guess both stages are the first. It's just a matter of which one you chose.

You have to activate all the switches in order to access the Special World from Star Road 5. You'll see why here.

It also just makes the game easier in general to have the switches activated. They provide you with more blocks to walk on.

Well, one has a 1 and the other has a 2, so it seems pretty clear which is level 1.

For years always thought it was the right path one.

But its technically the left path one since it is officially Yoshi's Island 1.

Yoshi's Island 1, because it's numbered as such (as previously posted)

You don't need to activate any switches to get to that key in Star Road 5. If you have a blue Yoshi, you can eat any Koopa Troopa and fly up to the key. I can't remember the last time I got to the Special World with all the palace switches activated. I usually go there as soon as possible once I get to Donut Plains.

Neither. The house is the first level.

Well level 1 is level 1 because level 2 can’t be level 1 otherwise level 3 would be level 2 as well.