First of all, he is neither a Monkey nor a Human. You can think of him as Supernatural. But since he incarnated on this earth, he lived a normal living-thing’s life.
From the Valmikis’ Ramayan to Ram charit Manas Hanuman knows all the Vededs, Purans and other Shaastras. A monkey can’t do this because of a lack of intelligence. Monkey can’t even speak, but it is written that Hanuman used to interact with others. Hence they were not Monkeys.
Monkeys include all the living creatures like Chimp, Orangutan, Langoor, Gorilla, etc.
They (Hanuman and his friends) are shown with a tail like Monkeys. We often refer to them as Vaanar.
The catch here is Vaanar word is not mentioned in Ramcharit Manas or any old books for Monkeys. Vaanar doesn’t mean Monkey or anything. In fact, there is a difference between Vaanar and Monkey(Bandar).
Hanuman was from the race called Kapi. Even today’s scientists proved from Carbon Dating and Fossils that Lakhs of years ago there existed a species called Neanderthal. They looked like Monkeys but were equal or even more intelligent than Humans(Homo Sapience).
That species extinct 12,000 to 15,000 years ago.
This also is proven by Charles Darwin’s theory. That species lived in Middle to South of India, Bangladesh, Myanmar, Malaysia & Indonesia. They originated in Africa, Middle East long ago and today we named them Neanderthal.
They looked similar to Monkeys and had the intelligence of Homo Sapience (today’s humans) & had more strength than Humans.
Neanderthals lived in Caves. We also know, Hanuman was born in Kishkindha in Karnataka, India. Even today there are lots of caves & mountains seen.
Fossils have proved Neanderthals and Homo Sapiens lived together, across Africa & India. They even talked together and bred together. Hanuman’s mother, Anjana, was a Homo Sapiens with no tail, while his father, Keshari, had a tail.
Same thing with Bali, Sugreev having Homo Sapiens wives while they were Neanderthal.
Homo Sapience came into existence 1,90,000 in Africa. 70,000 years ago they moved from Africa to India. Then, in India Homo Floresiensis lived.
Which got extinct and fossils are found in Indonesia.
In Madhya Pradesh of India, Homo Erectus’ fossils were found. They extincted 18 Lakhs years ago.
Similarly, many different species that looked between Monkey and Human are exinct now.
These all Carbon Dating and Darwin’s Theory matches as per mentioned in Ramayana. There were many similar species that looks like Monkey, but actually different. Even today you will find different races of Human that looks so primitive across the world.
So Neanderthal is species of Kapi i.e. the clan of Hanuman.
And yes they were Vaanar. Vann (Forest) + Nar(Man). The man who lives in Forest.