All I remember is it's mainly focused on this young kid, who I think is the villages sort of weakling and he goes on this journey to the mountain. There's a scene where he has to crawl through this really tight tunnel and it's completely dark and he's in there for days. I have a really strong feeling that buffalos or some animals along those lines is involved.

What level if reading waa the book at?

Of* was*

Honestly not sure, I think I read it when I was young but the book may have been aimed at young adults. It wasn't a children's book though

Rowan of Rin?

It was a 5 book series from the early to mid 90s.

Dammit that seems familiar to me now. At least the hole part.

Okay so I haven't found a book I recognize but here are my findings so far.
The Weirdstone of Brisingamen by Alan Garner
Rhapsody: Child of Blood (Symphony of Ages, #1) by Elizabeth Haydon
Goblins in the Castle by Bruce Coville
WAIT I FOUND A SERIES I REMEMBER, IDK IF IT'S IT BUT I HIGHLY RECOMMEND IT ANYWAY
The Underland Chronicles by Suzanne Colins

Also I just now found out that Suzanne Colins is the author of the Hunger Games... Really liked the Underland Chronicles tho

It sounds really familiar. Arghh upsets me now I can't think of it haha

LOOOOOOVE the Underland Chronicles. Definitely not the book being searched for though. Main character is from NYC no mountains or buffalo.

Pretty sure it is Rowan of Rin. It has mountains, a tunnel, big furry beasts...

Rowan of Rin sounds really familiar, I'm really hoping it's that so if it is thank you so much @strongsad. I'll have to read it again to make sure. It seems the most likely considering it would've been around the same time I was reading the Deltora's Quest series.
.
Thanks for your efforts guys! Even if it ends up being none of these I'll have some good books to read.

I’d recommend both Skulduggery Pleasant and the Truckers trilogy :)