I was trying to search for some information about the nature of monkey like characters in Ramayana and any related research about these beings called vanars.

Note that its not only monkey like beings, but also bear like beings that are mentioned in Ramayana.

Given the ancient timescale of Ramayana occurring in Treta yuga, were these some kind of hominid species.. like monkey-humans and bear-humans of prehistoric period?

Lord Sri Rama and Hanuman

And I stumbled upon this wonderful link. Of Monkeys, Men and Cataclysms by Blair A. Moffett.

Here it is stated that the monkeys in Ramayana could actually be Neanderthaloids who co-existed with the Homo-Sapiens then!

Also it has to be noted that, archaeological evidences suggest that Neanderthals lived in South India from about 5,00,000 to 40,000 years ago.

Similarly, I think the bear like beings like Jambavantha mentioned in Ramayana are what are known as Yetis in other parts of the world. Was it a group of Homo Erectus? Please see this link