Top part of the island?

[Camomile]

It's been a couple days now but I still haven't figured out how to get to the upper half of my island, I feel like I'm missing something super easy about it.

 

[Ashkraft]

It's been a couple days now but I still haven't figured out how to get to the upper half of my island, I feel like I'm missing something super easy about it.

Hello!

To cross the rivers you need to pole vault which you receive from Blathers once he makes it to your island.
To get up the cliffs you need the ladder. Which you receive from Tom Nook after you agree to help him build more things for incoming villagers.

Hope this helps without too many spoilers!

 

[JKDOS]

Everything should unlock as you progress in the story. That's the best I can say without giving apoilers