Are there any other simian primates to choose from? There's a lot of different apes.

I believe this easily usable for any large, tail-less simian such as an orangutan as well. 

I understand that you can use this stat block for multiple types of ape, but, for example, a bonobo male is on the high end, 130 lbs. but gorillas can be over 350 lbs. and Gigantopithicus can be nearly a ton! logically, there should be more types of apes with higher CR. But I can't find any.

Oh yeah, that might be a problem. Often if I need a specific creature for a specific setting (such as a dwarven commoner or a human mage), I copy the statblock into my notes and change it a bit for my own purposes. A Gigantopithicus, for example, could be considered a large creature instead of a medium creature, and it should probably have one or two extra hit dice. Edit the CR from 1/2 to 1, if you desire.

Homebrew them. Add a d4 to attacks and half the hit die to hp.

I think Gigantopithicus would use the "Giant Ape" stats. But lumping gorillas in with Bonobos (who can still be pretty scary if the want to) is a bit reductionist. 

I ship my bard and dis

Is it good to send 5 of these after 7 level 1 characters?

can you use this as a Beastmaster companion?

No.

So this is what my personal stats would like, interesting

I love going to the comments of the stats for just regular animals and seeing all the people who actually care about the details of them. It makes me happy.

With Multiattack, is it possible to do a Fist and Rock attack on one turn, or is the Multiattack only with 2 Fist attacks? So the Ape's attack choices would either be 2 Fist attacks or 1 Rock attack? I know it specifically says Fist on the Multiattack description but just wanted to be sure.

it would be two fists or one rock throw

I love turning into one of these for my Barbarian Druid. It fits soooo well!

ape

Reject Humanity

Wild Shape to Monke

-Big Chungus

Haha, I totally agree

Monke

Would this and a Firbolg be about the same shape and size? If a firbolg wildshaped into an ape, could it still wear the same armor?